Three-dimensional structure for wiring formation

ABSTRACT

One aspect of the present invention is a three-dimensional structure that has a concave-convex form including a gutter for wiring having at least partially a width of 20 μm or less, wherein at least a part of a wiring conductor is embedded in the gutter for wiring, and a wiring that extends in such a manner as to creep along the concave-convex form is provided.

TECHNICAL FIELD

The present invention mainly relates to a three-dimensional structurefor wiring formation.

BACKGROUND ART

Conventionally, a semiconductor device in which a semiconductor chip ismounted on an insulating base material is well known. As the method ofmounting a semiconductor chip on an insulating base material andelectrically connecting the semiconductor chip to an electrode padformed on the insulating base material surface, the wire bonding methodis widely used.

The wire connection method based on wire bonding is a method, as shownin FIG. 6, of mutually connecting a bonding pad 22 a formed on an uppersurface of a semiconductor chip 22 and an electrode pad 11 a on the sideof an insulating base material 11 via a wire 13 formed from gold, copperor the like and having a diameter of several 10 μm. More specifically,this is a method of connecting a wire protruding from the tip of acapillary through a throughhole formed at the center of a movablecapillary to one pad with the ultrasonic combination thermocompressionbonding method, and thereafter moving the capillary to the other padwhile pulling the wire out from the through hole, and connecting thewire to the pad with the ultrasonic combination thermocompressionbonding method while pressing the wire and the capillary against theother pad, and simultaneously breaking the wire.

According to the wire bonding method, as shown in FIG. 6, the bondingpad 22 a formed on the surface of the semiconductor chip 22 and theelectrode pad 11 a on the surface of the insulating base material 11 aremutually wire-connected with the wire having a diameter of roughlyseveral 10 μm. This kind of method entails the following problems.

Under normal circumstances, in the production process of a semiconductordevice, after the wire bonding process, the surface of the semiconductorchip is sealed with a seal material in order to protect thesemiconductor chip, and then packaged. The seal material that is used inthe foregoing sealing step usually contains large amounts of inorganicfilling material so as to provide sufficient insulation or to increasethe dimensional stability. Thus, the seal material containing largeamounts of inorganic filling material as described above has extremelyinferior fluidity. Consequently, after inserting a base material mountedwith a semiconductor chip into a mold and thereafter filling the sealmaterial inside the mold, it is necessary to perform the molding at anextremely high pressure. In such case, considerably external force isapplied to the wire used for the bonding, and there was a problem inthat the reliability of the semiconductor device would be impaired dueto the breakage or damage of the wire. In order to resolve this kind ofproblem, measures of increasing the wire diameter are also beingadopted. Nevertheless, expensive gold is often used as the wire. Thus,increasing the wire diameter means increased costs. In addition, withthe wire bonding method, since the wire spacing cannot be narrowed inconsideration of the sweep amount of the wire, there is a problem inthat the wiring density is low.

As an alternative method to the wire bonding, for example, the methoddescribed in following Non-Patent Document 1 is known. The outline isspecifically explained. (1) Foremost, a semiconductor chip that is fixedon a flexible substrate is coated with a silicon oxide film.Subsequently, an organic film for flattening the silicon oxide filmsurface is formed. Subsequently, a metal mask is used to remove thesilicon oxide film on the surface of the bonding pad of thesemiconductor chip surface and the surface of the electrode pad formedon the flexible substrate, and the organic film. (2) Subsequently, onlythe organic film of the other portions is removed. (3) Subsequently,plating seeds are attached to the entire surface, and a resist forplating is additionally formed so as to cover the plating seeds.Subsequently, a silicon oxide film is additionally formed on the surfaceof the resist for plating. Subsequently, an organic film for flatteningthe silicon oxide film surface is formed once again. (4) Subsequently, ametal mask is used to remove the silicon oxide film and the organic filmalong a path of the portion connecting the bonding pad and the electrodepad where the wiring should be formed. (5) Subsequently, with thesilicon oxide film as the mask, the plating seeds are exposed byremoving the resist for plating of the portions where the silicon oxidefilm is not formed. (6) Finally, by performing plating processing,plating is formed only at the portion where the plating seeds remainbased on the foregoing steps, and a wiring is thereby formed.

-   Non-Patent Document 1: Reference handout of MEMS-Semiconductor    Lateral Wiring Technique (Lecture of Mr. Mitsumasa Koyanagi,    Professor of Tohoku University, Graduate School of Engineering) in    Co-Hosted Program of 19th Micromachine/MEMS Exhibition of Fine MEMS    Project Interim Result Presentation (Jul. 31, 2008 at Tokyo Big    Site)

SUMMARY OF THE INVENTION

The present invention aims to resolve the foregoing problems in thewiring bonding that was conventionally used for connecting thesemiconductor chip disposed on the insulating base material surface tothe electrode pad formed on the insulating base material surface, andits object is to form, with an easy process, a wiring capable ofinhibiting the breakage or damage of the wire during the sealingperformed with the resin seal material.

Moreover, another object of this invention is to improve the adhesivestrength of the wiring relative to a three-dimensional structure inwhich a wiring is provided on its structure, and consequently reduceproblems such as the falling, dislocation and disconnection of thewiring.

One aspect of the present invention is a method of mounting asemiconductor chip for electrically connecting a bonding pad, which isprovided on a surface of a semiconductor chip disposed on an insulatingbase material surface, to an electrode pad corresponding to the bondingpad formed on the insulating base material surface, the methodcomprising: a coating forming step of forming a resin coating on asurface of a path connecting the bonding pad and the electrode pad; awiring gutter forming step of forming, by laser beam machining, a wiringgutter having a depth that is equal to or greater than a thickness ofthe resin coating along the path for connecting the bonding pad and theelectrode pad; a catalyst depositing step of depositing a platingcatalyst or a precursor thereof on a surface of the wiring gutter; acoating removing step of removing the resin coating by causing thiscoating to dissolve or swell in a predetermined liquid; and a platingprocessing step of forming, after the resin coating is removed, anelectroless plating coating only at a site where the plating catalyst ora plating catalyst formed from the plating catalyst precursor remains.

Another aspect of the present invention is a three-dimensional structurein which a wiring is formed on a surface, wherein, on the surface of thethree-dimensional structure, a recessed gutter for wiring is formed,extending between mutually intersecting adjacent faces or on a planarsurface or a curved surface of the three-dimensional structure, andwherein at least a part of a wiring conductor is embedded in therecessed gutter for wiring.

Yet another aspect of the present invention is a three-dimensionalstructure that has a concave-convex form including a gutter for wiringhaving at least partially a width of 20 μm or less, wherein at least apart of a wiring conductor is embedded in the gutter for wiring, and awiring that extends in such a manner as to creep along theconcave-convex form is provided.

The objects, aspects, features and advantages of the present inventionwill become more evident based on the ensuing detailed explanation andthe appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1C are diagrams explaining the first half of theprocesses in the method of mounting a semiconductor chip according tothe first embodiment of the present invention.

FIG. 2A to FIG. 2C are diagrams explaining the second half of theprocesses in the method of mounting a semiconductor chip according tothe first embodiment of the present invention.

FIG. 3 is a schematic diagram of the semiconductor device that isobtained by using the method of mounting a semiconductor chip accordingto the first embodiment of the present invention.

FIG. 4A to FIG. 4C are diagrams explaining the first half of theprocesses in the method of connecting semiconductor chips according tothe second embodiment of the present invention.

FIG. 5A to FIG. 5C are diagrams explaining the second half of theprocesses in the method of connecting semiconductor chips according tothe second embodiment of the present invention.

FIG. 6 is a schematic diagram schematically showing the mountingconfiguration of a conventional semiconductor device that iswire-connected based on the wire bonding method.

FIG. 7 is a diagram showing the state on the base material surface ofthe three-dimensional wiring obtained with the method described inNon-Patent Document 1.

FIG. 8A to FIG. 8E are process charts corresponding to FIG. 1B to FIG.1C or FIG. 4B to FIG. 4C and FIG. 2A to FIG. 2C or FIG. 5A to FIG. 5C incases of forming a wiring gutter having a depth that is the same as thethickness of the resin coating.

FIG. 9A to FIG. 9E are process charts corresponding to FIG. 1B to FIG.1C or FIG. 4B to FIG. 4C and FIG. 2A to FIG. 2C or FIG. 5A to FIG. 5C incases of forming a wiring gutter having a depth that is greater than thethickness of the resin coating.

FIG. 10A to FIG. 10C are diagrams showing modified examples of thewiring obtained in FIG. 9E.

FIG. 11A to FIG. 11C are process charts showing the wiring formingmethod using CMP treatment.

FIG. 12 is an enlarged perspective view showing the relevant part of thethree-dimensional structure in which a wiring is provided on its surfaceaccording to the third embodiment of the present invention.

FIG. 13 is an enlarged cross section showing a specific example of theconfiguration of the pad part in the three-dimensional structure.

FIG. 14A is an enlarged cross section showing an undesirable example ofthe configuration of the pad part in the three-dimensional structure,and FIG. 14B is an enlarged cross section showing a favorable examplethereof.

FIG. 15 is an enlarged perspective view showing the relevant part of thethree-dimensional structure in which a wiring is provided on its surfaceaccording to the fourth embodiment of the present invention.

FIG. 16 is a cross section showing the three-dimensional structure inwhich a wiring is provided on its surface (semiconductor device in whichthe semiconductor chip mounted on the insulating base material is coatedwith insulating resin) according to the fifth embodiment of the presentinvention.

FIG. 17A to FIG. 17C are cross sections explaining the first half of theprocesses in the method of producing the three-dimensional structureaccording to the fifth embodiment.

FIG. 18A to FIG. 18C are cross sections explaining the second half ofthe processes in the method of producing the three-dimensional structureaccording to the fifth embodiment.

FIG. 19A to FIG. 19C are cross sections showing mutually differentexamples of the three-dimensional structure in which a wiring isprovided on its surface (semiconductor device in which the semiconductorchip mounted on the insulating base material is coated with insulatingresin) according to the sixth embodiment of the present invention.

FIG. 20 is a cross section of a memory card as a specific example of thethree-dimensional structure in which a wiring is provided on its surface(semiconductor device in which the semiconductor chip mounted on theinsulating base material is coated with insulating resin) according tothe seventh embodiment of the present invention.

FIG. 21 is a cross section showing the magnetic head as a specificexample of the three-dimensional structure in which a wiring is providedon its surface (electrical device in which the passive element is coatedwith insulating resin) according to the eighth embodiment of the presentinvention.

FIG. 22 is a simplified diagram explaining a wiring width (L) and adistance between wirings (S) according to an embodiment of the presentinvention.

FIG. 23 is a simplified perspective view showing the relevant part ofthe three-dimensional structure in which a wiring is provided on itssurface according to the third (1) embodiment of the present invention.

FIG. 24 is a simplified perspective view showing a state in whichwirings are provided in the three-dimensional structure shown in FIG.23.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to studies conducted by the present inventors, a wiring forconnecting the electrode pad of the substrate surface and the bondingpad of the chip surface can be formed without using wire bonding basedon the method described in Non-Patent Document 1. Nevertheless, thiskind of method is unsuitable for mass production since complex, multipleprocesses are required. The present invention was devised based on theresults of the foregoing studies. The embodiments for implementing thisinvention are now explained in detail.

First Embodiment

The preferred embodiments of the method of mounting a semiconductor chipaccording to the present invention are now explained with reference tothe drawings.

FIG. 1 and FIG. 2 are schematic diagrams explaining the respectiveprocesses in the method of mounting a semiconductor chip of thisembodiment. Note that, in FIG. 1 and FIG. 2, 1 represents an insulatingbase material, 1 a represents an electrode pad, 2 represents asemiconductor chip, 2 a represents a bonding pad, 3 represents a resincoating, 4 represents a wiring gutter, 5 represents a plating catalyst,6 represents an electroless plating coating, and 7 represents a wiring.

In the production method of this embodiment, as shown in FIG. 1A,foremost, an insulating base material 1 mounted with a semiconductorchip 2 in a predetermined chip mounting area is prepared.

Note that the semiconductor chip 2 is fixed to the predetermined chipmounting area on the surface of the insulating base material 1 using anadhesive or the like, and the adhesive surface is filled with resin sothat no gaps will remain. Note that, as will be clarified later, inorder to prevent the wiring 7 made of an electroless plating coating 6from becoming directly formed on the silicon wafer (especially its sideface that was subject to dicing) of the semiconductor chip 2, forexample, it would be more preferable to at least preliminarily cover thepart of the semiconductor chip 2 where the wiring 7 will be formed withan insulating organic material such as resin or an insulating organicmaterial such as ceramics as represented by silica (SiO₂).

There is no particular limitation in the semiconductor chip, and an IC(Integrated Circuit), an LSI (Large Scale Integration), a VLSI (VeryLarge Scale Integration), or a light-emitting semiconductor chip such asan LED chip may be used.

Subsequently, as shown in FIG. 1B, a resin coating 3 is formed on thesurface of the semiconductor chip 2 and the insulating base material 1(coating forming step).

As the insulating base material 1, various organic base materials andinorganic base materials that have been conventionally used for mountinga semiconductor chip can be used without particular limitation. Asspecific examples of the organic base material, base materials made ofepoxy resin, acrylic resin, polycarbonate resin, polyimide resin,polyphenylene sulfide resin and the like can be used. The mode of thebase material may be a sheet, a film, a prepreg, a three-dimensionallyshaped compact or the like, and there is no particular limitation. Thereis no particular limitation in the thickness of the insulating basematerial 1. In the case of a sheet, a film or a prepreg, for example,the thickness is 10 to 200 μm, and more preferably around 20 to 100 μm.

As the method of forming the resin coating 3, there is no particularlimitation so as long as it is a method which at least forms the resincoating 3 on the surface of a path connecting the respective electrodepads 1 a and the respective bonding pads 2 a on the surface of theinsulating base material 1 and the surface of the semiconductor chip 2.Specifically, for example, adopted may be a method of applying andsubsequently drying a liquid material capable of forming the resincoating 3 on the entire surface where the semiconductor chip 2 of theinsulating base material 1 is disposed as shown in FIG. 1B. Moreover, asa separate method, adopted may be a method of transferring the resincoating 3 that was formed on the support base material in advance to thesurface of the insulating base material 1. There is no particularlimitation on the method of applying a resin fluid. Specifically, thedipping method or the spray method may be used.

The thickness of the resin coating 3 is 10 μm or less and preferably 5μm or less, and 0.1 μm or more and preferably 1 μm or more. If thethickness is too thick, the dimension accuracy tends to deteriorate uponpartially removing the resin coating 3 with laser beam machining, and,if the thickness is too thin, the formation of a coating with a uniformfilm thickness tends to be difficult.

As the material for forming the resin coating 3, any resin material thatcan be removed by dissolving or swelling in the removal processdescribed later can be used without particular limitation. Specifically,for example, resist resin that is used in the field of photoresist orresin with a high swelling level relative to a predetermined liquid andwhich can be peeled by swelling can be used.

As specific examples of the resist resin, there are, for example,photocurable epoxy resin, etching resist, polyester resin, and rhodineresin.

Moreover, as the swellable resin, preferably used is swellable resinhaving a swelling level relative to a predetermined liquid that is 50%or higher, or 100% or higher, or even 500% or higher. As specificexamples of the foregoing resin, for example, diene elastomer such asstyrene-butadiene copolymer, acrylic elastomer such as acrylic acidester copolymer, and polyester elastomer which have been adjusted to anintended swelling level by adjusting the degree of cross-linkage or thedegree of gelation can be used.

The resin coating 3 is additionally explained in further detail.

As the resin coating (resist) 3, there is no particular limitation so aslong as it can be removed in the removal process described later. Theresin coating 3 is preferably a resin coating that can be easily removedby being dissolved or peeled from the surface of the insulating basematerial 1 as a result of being dissolved or swelled with apredetermined liquid. Specifically, for example, a coating made ofsoluble resin that can be easily dissolved in an organic solvent or analkaline solution or a coating made of swellable resin that can beswelled in a predetermined liquid (swelling liquid) can be used. Notethat the swellable resin coating includes, in addition to a resincoating which substantially does not dissolve in a predetermined liquidbut can be easily peeled from the surface of the insulating basematerial 1 based on swelling, a resin coating which swells in apredetermined liquid and additionally in which at least a part thereofdissolves, and can be easily peeled from the surface of the insulatingbase material 1 based on such swelling and dissolution, and a resincoating which dissolves in a predetermined liquid, and can be easilypeeled from the surface of the insulating base material 1 based on suchdissolution. As a result of using this kind of resin coating, the resincoating 3 can be easily and favorably removed from the surface of theinsulating base material 1. If the resin coating is collapsed uponremoving the resin coating 3, there is a problem in that the platingcatalyst 5 that is deposited on the resin coating 3 will scatter, andthe scattered plating catalyst will be re-deposited on the insulatingbase material 1 and form unneeded plating at such portion. In thisembodiment, the foregoing problem can be prevented since the resincoating 3 can be easily and favorable removed from the surface of theinsulating base material 1.

There is no particular limitation on the method of forming the resincoating 3. Specifically, for example, a method of applying andsubsequently drying a liquid material capable of forming the resincoating 3 on the surface of the insulating base material 1, or a methodof transferring, to the surface of the insulating base material 1, theresin coating formed by applying and subsequently drying the liquidmaterial on the support base material can be used. Moreover, as anothermethod, a method of laminating a resin film made of a pre-formed resincoating 3 on the surface of the insulating base material 1 can also beused. Note that there is no particular limitation in the method ofapplying the liquid material. Specifically, for example, theconventionally known spin coat method and bar coater method can be used.

As the material for forming the resin coating 3, any resin material thatcan be easily removed by dissolution or swelling from the surface of theinsulating base material 1 by dissolving or swelling in a predeterminedliquid can be used without particular limitation. Preferably used isresin having a swelling level relative to a predetermined liquid that is50% or higher, or 100% or higher, or even 500% or higher. Note that, ifthe swelling level is too low, the peeling of the resin coating tends tobe difficult.

The swelling level (SW) of the resin coating can be obtained from theformula of “swelling level SW={(m(a)−m(b))/m(b)}×100(%)” based on thepre-swelling weight m(b) and the post-swelling weight m(a).

This kind of resin coating 3 can be easily formed based on a method ofapplying and subsequently drying a suspension or an emulsion of anelastomer on the surface of the insulating base material 1, or a methodof transferring, to the surface of the insulating base material 1, thecoating formed by applying and subsequently drying a suspension or anemulsion of an elastomer on the support base material.

As specific examples of the elastomer, diene elastomer such asstyrene-butadiene copolymer, acrylic elastomer such as acrylic acidester copolymer, and polyester elastomer may be used. According to thiskind of elastomer, a resin coating of an intended swelling level can beeasily formed by adjusting the degree of cross-linkage or degree ofgelation of the elastomer resin particles dispersed as the suspension orthe emulsion.

As this kind of resin coating 3, particularly, it is preferably acoating in which the swelling level changes depending on the pH of theswelling liquid. When this kind of coating is used, by causing theliquid condition in the catalyst depositing step described later and theliquid condition in the coating removing step described later to bedifferent, the resin coating 3 can maintain high adhesiveness to theinsulating base material 1 in the pH in the catalyst depositing step,and at the same time the resin coating 3 can be easily peeled andremoved from the insulating base material 1 in the pH in the coatingremoving step.

More specifically, for example, if the catalyst depositing stepdescribed later comprises a step of performing treatment in anacidic-catalyzed metal colloid solution within a range of pH 1 to 3, andthe coating removing step described later comprises a step of swellingthe resin coating in an alkaline solution within a range of pH 12 to 14,the resin coating 3 has preferably a swelling level relative to theacidic-catalyzed metal colloid solution that is 60% or less and morepreferably 40% or less, and has a swelling level relative to thealkaline solution that is 50% or higher, preferably 100% or higher, andmore preferably 500% or higher.

As examples of this kind of resin coating 3, a sheet formed from anelastomer containing a predetermined amount of carboxyl group, a sheetobtained by hardening the entire surface of a photocurable alkalinedevelopment-type resist that is used for a dry film resist (hereinaftersometimes referred to as the “DFR”) for the patterning of the printedwiring board, or a thermosettable or alkaline development-type sheet canbe used.

As specific examples of an elastomer containing a carboxyl group, dieneelastomer such as styrene-butadiene copolymer, acrylic elastomer such asacrylic acid ester copolymer, and polyester elastomer which contain acarboxyl group in the molecules as a result of containing a monomer unithaving a carboxyl group as a copolymerization component may be used.According to this kind of elastomer, a resin coating with an intendedalkali swelling level can be formed by adjusting the acid equivalent,degree of cross-linkage, degree of gelation or the like of an elastomerthat is dispersed as a suspension or an emulsion. Moreover, it ispossible to increase the swelling level relative to a predeterminedliquid in the coating removing step, and easily form a resin coatingthat dissolved in the foregoing liquid. The carboxyl group in theelastomer has the function of swelling the resin coating in the alkaliaqueous solution and peeling the resin coating 3 from the surface of theinsulating base material 1. Moreover, the acid equivalent is thepolymeric molecular weight per carboxyl group.

As the specific examples of a monomer unit having a carboxyl group,(meta)acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconicacid, maleic anhydride and the like may be used.

As the content ratio of the carboxyl group in the elastomer having sucha carboxyl group, it is 100 to 2000, and preferably 100 to 800 based onacid equivalent. If the acid equivalent is too small (if the number ofcarboxyl groups relatively too many), the compatibility with the solventor other compositions will deteriorate, and the resistance against thepretreatment liquid of the electroless plating tends to deteriorate.Moreover, if the acid equivalent is too large (if the number of carboxylgroups is relatively too few), the peelabilty relative to the alkaliaqueous solution tends to deteriorate.

Moreover, as the molecular weight of the elastomer, it is 10,000 to1,000,000, preferably 20,000 to 500,000, and more preferably 20,000 to60,000. If the molecular weight of the elastomer is too heavy, thepeelability tends to deteriorate, and, if it is too light, it becomesdifficult to maintain the uniformity of the thickness of the resincoating since the viscosity will deteriorate, and the resistance to thepretreatment liquid of the electroless plating also tends todeteriorate.

Moreover, as the DFR, for example, used may be a sheet of a photocurableresin composition including a photopolymerization initiator and uses, asits resin component, acrylic resin, epoxy resin, styrene resin, phenolicresin, urethane resin or the like containing a predetermined number ofcarboxyl groups. As specific examples of this kind of DFR, there are,for example, a sheet that is obtained by hardening the entire surface ofthe dry film of a photopolymerizable resin composition as described inJapanese Patent Application Laid-open No. 2000-231190, Japanese PatentApplication Laid-open No. 2001-201851, and Japanese Patent ApplicationLaid-open No. H11-212262, or the UFG series manufactured by Asahi KaseiCorporation that is commercially available as an alkalinedevelopment-type DFR.

In addition, as other examples of the resin coating 3, there are theresin containing carboxyl group and having rhodine as its main component(for example “NAZDAR229” manufactured by Yoshikawa Chemical), and theresin having phenol as its main component (for example “104F”manufactured by LEKTRACHEM).

The resin coating 3 can be easily formed by applying the suspension oremulsion of resin on the surface of the insulating base material 1 byusing a conventionally known application means such as the spin coatmethod or the bar coater method, and subsequently drying the same, or bylaminating the DFR formed on the support base material on the surface ofthe insulating base material 1 by using a vacuum laminator or the like,and thereafter hardening the entire surface.

Moreover, as the resin coating 3, for example, a resin coating having,as its main component, resin (carboxyl group-containing acrylic resin)made of acrylic resin containing a carboxyl group in which the acidequivalent is roughly 100 to 800 can also be preferably used.

Moreover, in addition to those described above, the following can alsobe preferably used as the resin coating 3. Specifically, the resistmaterial to configure the resin coating 3 required that, for example,(1) it possesses high resistance to the liquid (plating core applyingsolution) into which the insulating base material 1 formed with theresin coating 3 is dipped in the catalyst depositing step describedlater, (2) the resin coating (resist) 3 can be easily removed in thecoating removing step described later, for example, in the step ofdipping the insulating base material 1 formed with the resin coating 3in alkali, (3) it possesses high deposition properties, (4) a dry film(DFR) can be easily formed, and (5) it possesses high preservability. Asthe plating core applying solution, although described later, in thecase of an acidic Pd—Sn colloid catalyst system, for example, they areall acidic (for example, pH 1 to 3) aqueous solutions. Moreover, in thecase of an alkaline Pd ion catalyst system, the catalyst-providingactivator is weak alkali (pH 8 to 12), and the remainder are acidic.Accordingly, as the resistance to the plating core applying solution, itis necessary to withstand pH 1 to 11, and preferably pH 1 to 12. Notethat the term “to withstand” means that, when a sample deposited withthe resist is dipped in a chemical, the swelling and dissolving theresist is sufficiently suppressed, and fulfills the role as the resist.Moreover, generally speaking, the dipping temperature is roomtemperature to 60° C., the dipping time is 1 to 10 minutes, and theresist film thickness is roughly 1 to 10 μm, but these are not limitedthereto. As the chemical to be used for the alkali peeling in thecoating removing step, as described later, for example, a NaOH aqueoussolution or a sodium carbonate aqueous solution is generally used. ItspH is 11 to 14, and a resist film can be easily removed if the pH is 12to 14, and this is desirable. Generally speaking, the dipping or spraytreatment is performed under the following conditions; namely, the NaOHaqueous solution concentration is roughly 1 to 10%, the treatmenttemperature is room temperature to 50° C., and the treating time is 1 to10 minutes, but these are not limited thereto. Deposition properties arealso required for forming a resist on the insulting material. Uniformfilm formation without any eye holes and the like is required. Moreover,although a dry film is formed for the simplification of the productionprocess and reduction of material loss, the film needs to have bendperformance in order to ensure the handling properties. Moreover, aresist formed into a dry film is laminated on the insulating materialwith a laminator (roll, vacuum). The lamination temperature is roomtemperature to 160° C., and the pressure and time can be arbitrarilyset. Accordingly, viscosity is demanded during lamination. Thus, theresist formed as a dry film is usually formed as a three-layer structureby being sandwiched with a carrier film and a cover film also forpreventing the attachment of dust, but the configuration is not limitedthereto. As the preservability, storage at room temperature ispreferable, but storage in a refrigerator and a freezer is alsorequired. It is necessary to prevent the composition of the dry filmfrom separating or cracking due to deterioration in the bend performanceduring a low temperature.

From the foregoing perspective, as the resin coating 3, polymer resinthat can be obtained by polymerizing (a) at least one or more types ofmonomers of carboxylic acid or acid anhydride having at least onepolymerizable unsaturated group in the molecules, and (b) at least oneor more types of monomers that can be polymerized with the monomer of(a) above, or a resin composition containing such polymer resin may beused. As conventional technology, some examples are Japanese PatentApplication Laid-open No. H7-281437, Japanese Patent ApplicationLaid-open No. 2000-231190, Japanese Patent Application Laid-open No.2001-201851 and so on. As examples of the (a) monomer, (meta)acrylicacid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleicanhydride, half esterified maleic acid, butyl acrylate and the like maybe used, and these may be used alone or in combination of two or moretypes. As examples of the (b) monomer, generally used is a monomer thatis non-acidic and has (one) polymerizable unsaturated group in themolecules, but is not limited thereto. The (b) monomer is selected so asto retain the various characteristics such as resistance, flexibility ofthe hardened film and so on in the catalyst depositing step describedlater. Specifically, methyl(meta)acrylate, ethyl(meta)acrylate,iso-propyl(meta)acrylate, n-butyl(meta)acrylate,sec-butyl(meta)acrylate, tert-butyl(meta)acrylate,2-hydroxylethyl(meta)acrylate, 2-hydroxylpropyl(meta)acrylate and thelike may be used. Moreover, esters of vinyl alcohol such as vinylacetate, (meta)acrylonitrile, styrene or a polymerizable styrenederivative and the like may also be used. Moreover, this can also beobtained based only on the polymerization of carboxylic acid or acidanhydride having one of the foregoing polymerizable unsaturated groupsin the molecules. In addition, it is possible to select a monomer havinga plurality of unsaturated groups as the monomer for use as the polymerso as to enable a three-dimensional cross-link. Moreover, a reactivefunctional group such as the epoxy group, hydroxyl group, amino group,amide group, or vinyl group may be introduced into the molecular frame.

If a carboxyl group is contained in the resin, the amount of suchcarboxyl group contained in the resin is 100 to 2000 and preferably 100to 800 based on acid equivalent. If the acid equivalent is too low,compatibility with the solvent or other compositions will deteriorateand the plating pretreatment liquid resistance will deteriorate. If theacid equivalent is too high, the peelability will deteriorate. Moreover,the composition ratio of the (a) monomer is preferably 5 to 70 masspercent.

The resin composition has the polymer resin as the main resin (binderresin) as its essential component, and at least one type of oligomer,monomer, filler or other additives may be added thereto. The main resinis preferably linear-type polymer with thermoplastic property. There arealso cases where the grafting and branching are performed in order tocontrol the fluidity and crystallinity. The molecular weight is roughly1,000 to 500,000 and preferably 5,000 to 50,000 based on weight-averagemolecular weight. If the weight-average molecular weight is small, thebend performance of the film and the plating core applying solutionresistance (acid resistance) will deteriorate. Moreover, if themolecular weight large, the alkali peelability and lamination propertieswhen forming a dry film will deteriorate. In addition, a cross-link mayalso be introduced for improving the plating core applying solutionresistance, inhibiting the thermal deformation during laser beammachining, and controlling the fluidity.

As the monomer or oligomer, any monomer or oligomer may be used so aslong as it has resistance to the plating core applying solution and canbe easily removed with alkali. Moreover, the use as a plasticizing agentfor providing viscosity in order to improve the lamination properties ofthe dry film (DFR) can be considered. In addition, the addition of across-linking agent for increasing the various resistances can also beconsidered. Specifically, methyl(meta) acrylate, ethyl(meta)acrylate,iso-propyl(meta)acrylate, n-butyl(meta)acrylate,sec-butyl(meta)acrylate, tert-butyl(meta)acrylate,2-hydroxylethyl(meta)acrylate, 2-hydroxylpropyl(meta)acrylate and thelike may be used. Moreover, esters of vinyl alcohol such as vinylacetate, (meta)acrylonitrile, styrene or a polymerizable styrenederivative and the like may also be used. Moreover, this can also beobtained based only on the polymerization of carboxylic acid or acidanhydride having one of the foregoing polymerizable unsaturated groupsin the molecules. In addition, a multifunctional unsaturated compoundmay also be added. It may be the foregoing monomer or an oligomer thatwas reacted with the monomer. In addition to the foregoing monomers, twoor more types of photopolymerizable monomers can also be added. Asexamples of the monomer, there are 1,6-hexanediol di(meta)acrylate,1,4-cyclohexanediol di(meta) acrylate, or polypropyleneglycoldi(meta)acrylate, polyethylene glycol di(meta)acrylate, polyoxyalkyleneglycol di(meta)acrylate such as polyoxyethylene polyoxypropylene glycoldi(meta)acrylate, 2-di(p-hydroxyphenyl) propane di(meta)acrylate,glycerol tri(meta)acrylate, dipentaerythritol penta(meta)acrylate,trimethylolpropane polyglycidyl ether tri(meta)acrylate, bisphenol Adiglycidyl ether tri(meta)acrylate, 2,2-bis(4-methacryloxypentaethoxyphenyl) propane, multifunctional (meta)acrylate containing anurethane group, and the like. It may be the foregoing monomer or anoligomer that was reacted with the monomer.

Although there is no particular limitation in the filler, silica,aluminum hydroxide, magnesium hydroxide, calcium carbonate, clay,kaolin, titanium oxide, barium sulfate, alumina, zinc oxide, talc, mica,glass, potassium titanate, Wollastonite, magnesium sulfate, aluminumborate, organic filler and the like may be used. Moreover, since thepreferred thickness of the resist is thin at 0.1 to 10 μm, the fillersize is also preferably small. The filler preferably has a small averageparticle size with coarse grains removed therefrom, but the coarsegrains can also be pulverized during dispersion or removed withfiltering.

As other additives, photopolymerizable resin (photopolymerizationinitiator), polymerization inhibitor, coloring agent (dye, pigment,color-forming pigment), thermal polymerization initiator, cross-linkingagents such as epoxy and urethane may also be used.

In the wiring gutter forming step explained next, since the resincoating 3 is subject to laser beam machining and the like, it isnecessary to provide laser abrasion properties to the resist material. Alaser beam machine is selected, for example, among a carbon dioxidelaser, excimer laser, UV-YAG laser and the like. These laser beammachines respective have their own unique wavelength, and theproductivity can be improved by selecting materials with high UVabsorptance relative to the foregoing wavelengths. Among the above, theUV-YAG laser is suitable for microfabrication, and, since the laserwavelength is a third harmonic of 355 nm and a fourth harmonic of 266nm, the resist material (material of the resin coating 3) desirably hasa relatively high UV absorptance relative to these wavelengths. As theUV absorptance becomes higher, the processing of the resist (resincoating 3) can be finished cleanly, and the productivity can also beimproved. However, without limitation to the above, there are caseswhere a resist material having a relatively low UV absorptance isselected. As the UV absorptance becomes lower, since the UV light passesthrough the resist (resin coating 3), the UV energy can be concentratedon the processing of the insulating base material 1 therebelow, and, forexample, this yields particularly favorable results when the insulatingbase material 1 is a material that is difficult to process. Accordingly,the resist material is preferably designed based on the ease of laserbeam machining of the resist (resin coating 3), ease of laser beammachining of the insulating base material 1, and their relationship andthe like.

Subsequently, as shown in FIG. 1C, a wiring gutter 4 having a depth thatis equal to or greater than the thickness of the formed resin coating 3is formed (wiring gutter forming step). The wiring gutter 4 is formed bylaser beam machining along a path connecting the respective bonding pads2 a on the surface of the semiconductor chip 2 and the respectiveelectrode pads 1 a formed on the surface of the insulating base material1 to be connected to the respective bonding pads 2 a.

The wiring gutter 4 is formed along the path for connecting therespective bonding pads 2 a and the respective electrode pads 1 a asdescribed above. As a result of forming the wiring gutter 4 as describedabove, a wiring is formed as a result of the electroless plating coating6 being formed only on the surface of the portion where the wiringgutter 4 was formed in the subsequent process.

Subsequently, as shown in FIG. 2A, a plating catalyst 5 is deposited onthe surface where the wiring gutter 4 was formed (catalyst depositingstep).

The plating catalyst 5 is a catalyst that is provided for forming aplating film only at the portion where the electroless plating coating 6should be formed in the plating processing step described later. As theplating catalyst, conventionally known catalysts for electroless platingcan be used without any particular limitation. Moreover, it is alsopossible to deposit a precursor of the plating catalyst in advance andgenerate the plating catalyst after the removal of the resin coating 3.As specific examples of the plating catalyst, for example, metalpalladium (Pd), platinum (Pt), silver (Ag) and the like, or a precursorand the like that can be generated therefrom can be used.

As the method of depositing the plating catalyst 5, for example, amethod of treating in an acidic Pd—Sn colloid solution with the acidicconditions of pH 1 to 3, and thereafter treating in an acid solution canbe used. More specifically, the following method can be used. Foremost,the oils and the like that adhered to the surface of the portion wherethe wiring gutter 4 was formed is dipped in a surfactant solution(cleaner conditioner) and washed with hot water. Subsequently, asneeded, soft etching is performed with a sodium persulfate-sulfuric acidsoft etching agent. Then, it is further pickled in an acidic solutionsuch as a sulfuric acid aqueous solution or a hydrochloric acid aqueoussolution of pH 1 to 2. Subsequently, after dipping this in a pre-dipliquid having a tin chloride aqueous solution or the like having aconcentration of roughly 0.1% as its main component and adsorbing tinchloride, it is further dipped in an acidic-catalyzed metal colloidsolution such as an acidic Pd—Sn colloid of pH 1 to 3 containing tinchloride and palladium chloride so as to flocculate and adsorb Pd andSn. Subsequently, an oxidation-reduction reaction(SnCl₂+PdCl₂→SnCl₄+Pd↓) is generated between the adsorbed tin chlorideand palladium chloride. Metal palladium as the plating catalyst isthereby precipitated.

Note that, as the acidic-catalyzed metal colloid solution, a publiclyknown acidic Pd—Sn colloid catalyst solution and the like may be used,or a commercially available plating processing using an acidic-catalyzedmetal colloid solution may be used. This kind of process, for example,is being systemized and sold by Rohm and Haas Electronic Materials.

Through this kind of catalyst deposit treatment, as shown in FIG. 2A,the plating catalyst 5 is deposited on the surface of the wiring gutter4 and the surface of the resin coating 3.

Subsequently, as shown in FIG. 2B, the resin coating 3 is removed fromthe surface of the insulating base material 1 and the semiconductor chip2 by dissolving or swelling it in a predetermined liquid (coatingremoving step). According to this process, it is possible to cause theplating catalyst 5 to remain only on the surface of the portion wherethe wiring gutter 4 was formed on the surface of the insulating basematerial 1 and the semiconductor chip 2. Meanwhile, the plating catalyst5 that was deposited on the surface of the resin coating 3 other thanthe portion where the wiring gutter 4 was formed will be removed whenthe resin coating 3 is removed.

As the method of removing the resin coating 3 based on swelling ordissolution, a method of dipping the resin coating 3 in a predeterminedswelling liquid or dissolution liquid for a predetermined period of timecan be used. Moreover, it is particularly preferable to performultrasonic irradiation during the dipping in order to increase thepeelability and the dissolvability. Note that, in the case of peelingbased on swelling, it may be separated using light force as needed.

As the liquid for causing the resin coating 3 to dissolve or swell,there is no particular limitation so as long as it is a liquid in whichthe resin coating 3 can be easily peeled based on dissolution orswelling without substantially decomposing or dissolving the insulatingbase material 1 and the plating catalyst 5. Specifically, in the case ofusing the photocurable epoxy resin as the resist resin, a resist removerof an organic solvent or an alkali aqueous solution is used. Moreover,for example, if an elastomer such as a diene elastomer, an acrylicelastomer or a polyester elastomer is used as the swellable resin, analkali aqueous solution such as a sodium hydroxide aqueous solutionhaving a concentration of roughly 1 to 10% can be preferably used.

Moreover, if polymer resin that can be obtained by polymerizing (a) atleast one or more types of monomers of carboxylic acid or acid anhydridehaving at least one polymerizable unsaturated group in the molecules,and (b) at least one or more types of monomers that can be polymerizedwith the monomer of (a) above, or a resin composition containing suchpolymer resin, or the foregoing carboxyl group-containing acrylic resinis used as the resin coating 3, for example, an alkali aqueous solutionsuch as a sodium hydroxide aqueous solution having a concentration ofroughly 1 to 10% can be preferably used.

Upon using the plating process that is performed based on the foregoingacidic conditions in the catalyst depositing step, the resin coating 3is preferably formed from an elastomer such as a diene elastomer, anacrylic elastomer or a polyester elastomer having a swelling level of60% or less and preferably 40% or less under acidic conditions, and aswelling level of 50% or higher under alkaline conditions, or polymerresin that can be obtained by polymerizing (a) at least one or moretypes of monomers of carboxylic acid or acid anhydride having at leastone polymerizable unsaturated group in the molecules, and (b) at leastone or more types of monomers that can be polymerized with the monomerof (a) above, or a resin composition containing such polymer resin, orformed from the foregoing carboxyl group-containing acrylic resin. Thiskind of resin coating can be easily dissolved or swelled andsubsequently removed by dissolution or peeling by being dipped in analkali aqueous solution of pH 11 to 14 and preferably pH 12 to 14, forexample, a sodium hydroxide aqueous solution having a concentration ofroughly 1 to 10%. Note that ultrasonic irradiation may be performedduring the dipping in order to increase the dissolvability or thepeelability. Moreover, the resin coating can also be removed by beingseparated using light force as needed.

By adding a fluorescent substance to the resin coating in advance, thecoating removal failure can be inspected by using the emission of lightfrom the fluorescent substance as a result of irradiating ultravioletlight or near-ultraviolet light on the inspection target surface afterthe foregoing coating removing step (inspecting step). In thisembodiment, a metal wiring with an extremely narrow wiring width (e.g.,20 μm or less) can be formed. In the foregoing case, there is concernthat the resin coating between the adjacent metal wirings will remain asa result of not being completely removed. If the resin coating remainsbetween the metal wirings, a plating film will be formed at suchportion, and this may cause a short circuit. In the foregoing case, byadding a fluorescent substance to the resin coating 3 in advance, andirradiating a predetermined light emitting source on the coating removalsurface after the coating removing step and causing only the portionwhere the coating remains to emit light with the fluorescent substance,it is possible to inspect the existence of a coating removal failure orthe location of a coating removal failure.

The fluorescent substance that may be added to the resin coating 3 isnot particularly limited so as long as it shows light-emittingcharacteristics by irradiating light from a predetermined light source.As specific examples thereof, for example, there are Fluoresceine,Eosine, Pyronine G and the like.

The portion where the emission of light from the fluorescent substanceis detected in the inspecting step is the portion where the resincoating 3 will remain. Accordingly, as a result of removing the portionwhere the emission of light was detected, it is possible to inhibit theformation of the plating film on such portion. It is thereby possible toinhibit short circuits from occurring.

Subsequently, as shown in FIG. 2C, an electroless plating coating 6 isformed only at the site where the plating catalyst 5 remains (platingprocessing step). Based on this kind of process, it is possible toprecipitate the electroless plating coating 6 only at the portion wherethe wiring gutter 4 is formed. Based this kind of electroless platingcoating 6, the wiring 7 for electrically connecting the respectiveelectrode pads 1 a and each of the plurality of bonding pads 2 a on thesurface of the semiconductor chip 2.

As the method of the electroless plating processing, a method of dippingthe insulating base material 1 mounted with the semiconductor chip 2deposited with the plating catalyst 5 in an electroless plating solutionbath, and precipitating the electroless plating coating 6 only at theportion where the plating catalyst 5 was deposited.

As the metals to be used in the electroless plating, copper (Cu), nickel(Ni), cobalt (Co), aluminum (Al) and the like may be used. Among theabove, plating with Cu is preferably used as the main component since ithas superior conductivity. Moreover, in the case of containing Ni, it ispreferable since it has superior corrosion resistance and adhesivenesswith a solder.

Through this kind of plating processing, the electroless plating coating6 is precipitated only at the portion where the plating catalyst 5 onthe surface of the path connecting the respective bonding pads 2 a andthe respective electrode pads 1 a remains. Consequently, the wiring 7for connecting the respective bonding pads 2 a and the respectiveelectrode pads 1 a is formed. Since the portion where the wiring gutter4 is not formed is protected by the resin coating 3 from being depositedwith the plating catalyst 5, the electroless plating coating 6 is notprecipitated thereon. Accordingly, even when forming a thin wiring,unneeded plating films will not remain between the adjacent wirings, andshort circuits and the like can be inhibited.

With the formation of the plating film for the wiring, a thick platingfilm can be formed by using only the process of the electroless platingas described above, but the well-known electrolytic plating may also beconcurrently used in order to shorten the cycle time of the process(electrolytic plating step). Specifically, for example, by causing theelectroless plating formed in the foregoing process to be in conductionwith the anode side in an electrolytic plating bath and flowing currentbetween the electroless plating and the anode-side electrode, theportion where the electroless plating coating 6 is formed is thickened.According to this kind of method, since the thickening time can beshortened, the time required for forming the plating film can beshortened.

Although there is no particular limitation in the film thickness of theplating film formed as described above, specifically, for example, thefilm thickness is 0.1 to 10 μm, and more preferably around 1 to 5 μm.

Through the foregoing process, as shown in FIG. 2C, the formation inwhich the semiconductor chip 2 is mounted on the surface of theinsulating base material 1 is formed.

The formation in which the semiconductor chip 2 is mounted on thesurface of the insulating base material 1 as described above ispreferably subject to resin sealing for protecting its surface by usinga method such as insert molding. For this kind of sealing, the sealingmethods that have been conventionally used in the production process ofsemiconductor devices may be used without particular limitation.

FIG. 3 shows an explanatory diagram of the semiconductor device 20obtained as a result of sealing, with the sealing material 8, theformation 10 obtained by connecting all bonding pads 2 a of thesemiconductor chip 2 to the electrode pads 1 a based on the foregoingprocess. As shown in FIG. 3, a semiconductor chip 2 is disposed on thesurface of the insulating base material 1 in the formation 10. Inaddition, the plurality of bonding pads 2 a provided on the surface ofthe semiconductor chip 2 are respectively connected to the electrodepads 1 a formed on the surface of the insulating base material 1 by thewiring 7 made from a plating film. The wiring 7 is formed so as to creepalong the side face of the semiconductor chip 2 and the surface of theinsulating base material 1. Thus, even in cases of producing thesemiconductor device 20 by inserting the formation 10 into the mold andperforming resin sealing thereto, considerably force is not applied onthe wiring. Accordingly, no phenomenon will arise where the wire issubject to a load in the formation that was wire-connected via wirebonding.

Second Embodiment

A preferred method of connecting a plurality of semiconductor chipsaccording to the present invention is now explained with reference tothe drawings. Note that, since the respective processes are the same asthe processes explained in the first embodiment, the detailedexplanation of redundant portions is omitted. Moreover, since thecomponents given the same reference numerals as the reference numeralsof the first embodiment are the same components, the explanation thereofis omitted.

FIG. 4 and FIG. 5 are schematic diagrams explaining the respectiveprocesses in the method of connecting a plurality of semiconductor chipsof this embodiment. In FIG. 4 and FIG. 5, 1 represents an insulatingbase material, 2 represents a first semiconductor chip, 12 represents asecond semiconductor chip, 2 a, 12 a represent bonding pads, 3represents a resin coating, 4 represents a wiring gutter, 5 represents aplating catalyst, and 6 represents an electroless plating coating.

In the production method of this embodiment, as shown in FIG. 4A,foremost, the insulating base material 1 in which the firstsemiconductor chip 2 and the second semiconductor chip 12 disposed on apredetermined chip mounting area is prepared.

The first semiconductor chip 2 and the second semiconductor chip 12 arefixed to the predetermined chip mounting area on the surface of theinsulating base material 1 using an adhesive or the like, and theadhesive surface is filled with resin so that no gaps will remain. Inthis case also, in order to prevent the wiring 17 made of an electrolessplating coating 6 from becoming directly formed on the silicon wafer(especially its side face that was subject to dicing) of thesemiconductor chips 2, 12, for example, it would be more preferable toat least preliminarily cover the part of the semiconductor chips 2, 12where the wiring 17 will be formed with an insulating organic materialsuch as resin or an insulating organic material such as ceramics asrepresented by silica (SiO₂).

Then, as shown in FIG. 1B, a resin coating 3 is formed on the surface ofthe first semiconductor chip 2, the second semiconductor chip 12 and theinsulating base material 1 (coating forming step).

As the method of forming the resin coating 3, there is no particularlimitation so as long as it is a method which at least forms the resincoating 3 on the surface of the insulating base material 1 and thesemiconductor chips 2, 12 of a path connecting the bonding pads 2 a andthe bonding pads 12 a on the surface of the insulating base material 1,the surface of the first semiconductor chip 2 and the surface of thesecond semiconductor chip 12.

Subsequently, as shown in FIG. 4C, a wiring gutter 4 having a depth thatis equal to or greater than the thickness of the formed resin coating 3is formed (wiring gutter forming step). The wiring gutter 4 is formed,with laser beam machining, along a path for connecting the bonding pads2 a on the surface of the first semiconductor chip 2 and the bondingpads 12 a on the surface of the second semiconductor chip 12.

The wiring gutter 4 is formed along the path for connecting the bondingpads 2 a and the bonding pads 12 a as described above. As a result offorming this kind of wiring gutter 4, a wiring is formed by theelectroless plating coating 6 only being formed on the surface of theportion where the wiring gutter 4 is formed in the subsequent process.

Subsequently, as shown in FIG. 5A, a plating catalyst 5 is deposited ona surface on which the wiring gutter 4 is at least formed (catalystdepositing step). Based on this kind of catalyst depositing treatment,the plating catalyst 5 is deposited on the surface of the wiring gutter4 and the surface of the resin coating 3.

Subsequently, as shown in FIG. 5B, the resin coating 3 is removed fromthe surface of the insulating base material 1, the first semiconductorchip 2 and the second semiconductor chip 12 by being dissolved orswelled in a predetermined liquid (coating removing step). According tothis process, it is possible to cause the plating catalyst 5 to remainonly on the surface of the portion where the wiring gutter 4 was formedon the surface of the insulating base material 1, the firstsemiconductor chip 2 and the second semiconductor chip 12. Meanwhile,the plating catalyst 5 that was deposited on the surface other than theportions where the wiring gutter 4 was formed is removed upon removingthe resin coating 3.

Subsequently, as shown in FIG. 5C, an electroless plating coating 6 isformed only at the site where the plating catalyst 5 remains (platingprocessing step). Based on this kind of process, the electroless platingcoating 6 is precipitated only on the portion where the wiring gutter 4was formed. As a result of this kind of electroless plating coating 6, awiring 17 for electrically connecting the bonding pads 2 a and thebonding pads 12 a is formed.

Through this kind of plating processing, the electroless plating coating6 is precipitated only at the portion where the plating catalyst 5remains on the surface of the path connecting the bonding pads 2 a, 2 aof the first semiconductor chip 2 and the bonding pads 12 a, 12 a of thesecond semiconductor chip 12. The wiring 17 for connecting the bondingpads 2 a and the bonding pads 12 a is thereby formed. As a result ofperforming this kind of process, a formation in which the firstsemiconductor chip 2 and the second semiconductor chip 12 mounted on thesurface of the insulating base material 1 are electrically connected asshown in FIG. 5C is thereby formed.

According to this kind of connection method, since the wiring can beformed over the difference in level caused by the semiconductor chip,the plurality of semiconductor chips formed on the substrate can beelectrically connected mutually with a simple method. Accordingly, amulti chip module or the like in which a plurality of semiconductorchips are integrated can be realized easily.

Third (1) Embodiment

According to the method described in the Non-Patent Document 1, a wiringfor connecting the insulating base material and the semiconductor chipdisposed on a surface of the insulating base material can be formedthree-dimensionally across the insulating base material surface and thesemiconductor chip surface along the upper surface of the semiconductorchip, the side wall of the semiconductor chip, and the surface of theinsulating base material. In other words, the wiring is formedthree-dimensionally across two or more adjacent faces on the surface ofthe three-dimensional structure in which a semiconductor chip isdisposed on the surface of the insulating base material. Accordingly,the three-dimensional wiring formed as described above will be strongerthan the wiring formed based on wire bonding since it is formed in amanner of creeping along the surface while being in contact with thesurface of the insulating base material and the semiconductor chip, andis able to inhibit the damage of the wiring caused by the resin pressureduring the resin sealing.

Nevertheless, according to studies conducted by the present inventors,since the three-dimensional wiring obtained with the method described inNon-Patent Document 1 is in a state where the plated metal configuringthe wiring is merely placed on the base material surface or the chipsurface while being in contact with such surface as shown in FIG. 7, theadhesive strength of the wiring to the base material and the chip isweak, and there is a problem in that the wiring easily falls from thebase material surface or the chip surface or easily becomes dislocatedon the surface. In particular, the three-dimensional structure includesa corner part of a mountain line protruding outward, and, for example,if the wiring passes through such corner part such as a corner partwhere the upper surface and the side wall of the chip intersect, thewiring will be in a state of protruding further outward than the cornerpart. Thus, if the adhesive strength of the wiring is weak, the wiringwill be even more susceptible to falling or dislocation due to externalforce. Moreover, if the plated metal is merely placed on the surface ofthe base material or the like, since most of the plated metal will beexposed to the outside, the wiring is easily disconnected due to therepetition of expansion and contraction caused by heat or as a result ofbeing subject to physical external force such as vibration, and there isa possibility that it may lose its reliability as an electricalcomponent. This kind of problem is more prone to occur as the line widthof the wiring becomes thinner and narrower.

The present invention was devised based on the results of the foregoingstudies. Accordingly, another object of this invention is to improve theadhesive strength of the wiring relative to a three-dimensionalstructure in which a wiring is provided on its structure, andconsequently reduce problems such as the falling, dislocation anddisconnection of the wiring. Details of the third embodiment of thepresent invention are now explained.

At first, if a wiring gutter having a depth that is equal to thethickness of the resin coating in the first embodiment and the secondembodiment, generally speaking, the wiring is formed as follows.Specifically, as shown in FIG. 8A, in the coating forming step, a resincoating 102 is formed on a surface of an insulating base material 101(although this may also be a semiconductor chip, the insulating basematerial is used as a representative example for the sake ofconvenience; hereinafter the same). Subsequently, as shown in FIG. 8B,in the wiring gutter forming step, a wiring gutter 103 having a depththat is equal to the thickness of the resin coating 102 is formed alonga wiring path with laser beam machining. Here, a recessed gutter forwiring is not formed on a surface of the insulating base material 101.In other words, the surface of the insulating base material 101 is notcut. Subsequently, as shown in FIG. 8C, in the catalyst depositing step,a plating catalyst 104 is deposited on a surface of the wiring gutter103 and a surface of the resin coating 102. The plating catalyst 104 isdeposited on a surface of the insulating base material 101.Subsequently, as shown in FIG. 8D, in the coating removing step, theresin coating 102 is removed by being dissolved or swelled in apredetermined liquid. Then, as shown in FIG. 8E, in the platingprocessing step, a plated metal 105 is precipitated with electrolessplating so as to form the wiring 106 only at a site where the platingcatalyst 104 remains. The plated metal 105 is precipitated on thesurface of the insulating base material 101.

In the foregoing case, as shown in FIG. 8E, the plated layer 105 as thewiring conductor configuring the wiring 106 is in a state of merelybeing placed on the surface of the insulating base material 101 or thesurface of the semiconductor chip while being in contact with suchsurface. This state is the same as the state of the wiring (refer toFIG. 7) that is obtained with the method described in foregoingNon-Patent Document 1. In such state, the adhesive strength of thewiring 106 to the insulating base material 101 or the semiconductor chipis weak, and there is a problem in that the wiring 106 easily falls fromthe surface of the insulating base material 101 or the surface of thesemiconductor chip. Moreover, the wiring 106 easily becomes dislocatedon the surface of the insulating base material 101 or the surface of thesemiconductor chip. In particular, a three-dimensional structure such asa semiconductor device in which a semiconductor chip is mounted on theinsulating base material 101 includes a corner part of a mountain lineprotruding outward, and, for example, if the wiring 106 passes throughsuch corner part such as a corner part where the upper surface and thevertical side wall of the semiconductor chip intersect as shown in FIG.2C or FIG. 5C, the wiring 106 will be in a state of protruding furtheroutward than the corner part. Thus, if the adhesive strength of thewiring 106 is weak, the wiring 106 will be even more susceptible tofalling or dislocation due to external force. Moreover, if the platedmetal 105 is merely placed on the surface of the insulating basematerial 101 or the semiconductor chip, since most of the plated metal105 will be exposed to the outside, the wiring 106 is easilydisconnected due to the repetition of expansion and contraction causedby heat or as a result of being subject to physical external force suchas vibration, and there is a possibility that it may lose itsreliability as an electrical component.

Meanwhile, if a wiring gutter having a depth that is greater than thethickness of the resin coating in the first embodiment and the secondembodiment, generally speaking, the wiring is formed as follows.Specifically, as shown in FIG. 9A, in the coating forming step, a resincoating 102 is formed on a surface of an insulating base material 101.Subsequently, as shown in FIG. 9B, in the wiring gutter forming step, awiring gutter 103 having a depth that is greater than the thickness ofthe resin coating 102 is formed along a wiring path with laser beammachining. Here, the portion exceeding the thickness of the resincoating 102 in the wiring gutter 103 is formed as a recessed gutter forwiring on the surface of the insulating base material 101. Subsequently,as shown in FIG. 9C, in the catalyst depositing step, a plating catalyst104 is deposited on a surface of the wiring gutter 103 and a surface ofthe resin coating 102. The plating catalyst 104 is also deposited in therecessed gutter for wiring. Subsequently, as shown in FIG. 9D, in thecoating removing step, the resin coating 102 is removed by beingdissolved or swelled in a predetermined liquid. The plating catalyst 104in the recessed gutter for wiring will remain. Then, as shown in FIG.9E, in the plating processing step, a plated metal 105 is precipitatedwith electroless plating so as to form the wiring 106 at a site onlywhere the plating catalyst 104 remains. The plated metal 105 isprecipitated in the recessed gutter for wiring and fills the recessedgutter for wiring.

In the foregoing case, as shown in FIG. 9E, the plated metal 105 as thewiring conductor configuring the wiring 106 becomes a state of beingembedded in a recessed grove for wiring that is formed on the surface ofthe insulating base material 101 or the surface of the semiconductorchip. Accordingly, the adhesive strength of the wiring 106 to theinsulating base material 101 and the semiconductor chip will improve.Consequently, even if the wiring 106 passes through the corner part of amountain line protruding outward of the three-dimensional structure,problems such as the falling and dislocation of the wiring 106 can bereduced. Moreover, since the plated metal 105 is embedded in therecessed gutter for wiring, problems such as the wiring 106 beingdisconnected due to physical external force can also be reduced.

Although FIG. 9E is an example of the wiring 106 in which the entireplated metal 105 as the wiring conductor is embedded in the recessedgutter for wiring, and the surface of the plated metal 105 and thesurface of the insulating base material 101 are flush, the configurationis not limited thereto, and, for example, as shown in FIG. 10A, it mayalso be a wiring 106 in which the entire plated metal 105 is embedded inthe recessed gutter for wiring, but the surface of the plated metal 105is not flush with the surface of the insulating base material 101 and isretreated more inward of the recessed gutter for wiring. Moreover, asshown in FIG. 10B, it may also be a wiring 106 in which a part of theplated metal 105 is embedded in the recessed gutter for wiring, but theremaining portions of the plated metal 105 are protruding outside thesurface of the insulating base material 101. Moreover, as shown in FIG.10C, even if the amount of the other portions of the plated metal 105protruding outside the surface of the insulating base material 101 isrelatively large, so as long as a part of the plated metal 105 isembedded in the recessed gutter for wiring, it falls within the scope ofthe present invention, and yields the effect of the present invention.

Moreover, as shown in FIG. 9E and FIG. 10A, the wiring 106 in which theentire wiring conductor 105 is embedded in the recessed gutter forwiring can also be obtained based on embedded wiring formationtechniques using CMP (Chemical Mechanical Polishing) treatment.Specifically, as shown in FIG. 11A, a wiring gutter 103 is formed as arecessed gutter for wiring on the surface of the insulating basematerial 101, subsequently, as shown in FIG. 11B, a wiring conductor 105is formed inside the wiring gutter 103 and on the surface of theinsulating base material 101 so as to fill the wiring gutter 103, and,subsequently, as shown in FIG. 11C, the wiring conductor 105 outside thewiring gutter 103 is removed with the CMP treatment so as to form awiring 106 in which the entire wiring conductor 105 is embedded in therecessed gutter for wiring.

Accordingly, based on the above, this third embodiment relates to athree-dimensional structure 200 in which a wiring 106 is provided on itssurface as shown in FIG. 12, wherein a recessed gutter for wiring 103extending between the mutually intersecting adjacent faces 200 a, 200 b,200 c or on a planar surface or a curved surface (including a bentcurved surface, a concave curved surface, a convex curved surface, and acurved surface of the combinations thereof) of the three-dimensionalstructure 200 is formed on the surface of the three-dimensionalstructure 200, and at least a part of the wiring conductor 105 isembedded in the recessed gutter for wiring 103. Note that, at least apart of the wiring conductor 105 may be embedded in the recessed gutterfor wiring 103 across the entire length of the recessed gutter forwiring 103, or it may be embedded at one portion, embedded at aplurality of portions, or embedded partially or intermittently in theentire length of the recessed gutter for wiring 103.

As specific examples of the three-dimensional structure 200, there arethe following:

(1) A semiconductor device in which a semiconductor chip is mounted onan insulating base material as in the first embodiment (as describedabove, in order to prevent the wiring made of an electroless platingcoating from becoming directly formed on the silicon wafer (especiallyits side face that was subject to dicing) of the semiconductor chip, forexample, it would be more preferable to at least preliminarily cover thepart of the semiconductor chip where the wiring will be formed with aninsulating organic material such as resin or an insulating organicmaterial such as ceramics as represented by silica (SiO₂));(2) A three-dimensionally-shaped circuit board;(3) A multilayered circuit board;(4) A stacked chip package in which a plurality of semiconductor chipsare mounted on an insulating base material in a state of being stackedin multiple stages (in this case also, in order to prevent the wiringmade of an electroless plating coating from becoming directly formed onthe silicon wafer (especially its side face that was subject to dicing)of the semiconductor chip, for example, it would be more preferable toat least preliminarily cover the part of the semiconductor chip wherethe wiring will be formed with an insulating organic material such asresin or an insulating organic material such as ceramics as representedby silica (SiO₂));(5) A semiconductor device configured such that a semiconductor chip(for instance, a memory package or the like) that is mounted on aninsulating base material or a semiconductor chip that is not mounted onan insulating base material is coated with insulating resin (aninsulating organic material such as resin or an insulating organicmaterial such as ceramics as represented by silica (SiO₂) may also beused in substitute for the insulating resin);(6) A memory card in which the memory package is mounted on a supportmedium;(7) An electrical device (for instance, a magnetic head or the like)configured such that a passive element (for instance, a resistor, acapacitor, a coil, various sensors or the like) that is mounted on aninsulating base material or a passive element that is not mounted on aninsulating base material is coated with insulating resin (an insulatingorganic material such as resin or an insulating organic material such asceramics as represented by silica (SiO₂) may also be used in substitutefor the insulating resin); and(8) A magnetic head module or the like in which the magnetic head ismounted on a harness.

Then, on the surface of the three-dimensional structure 200, formed is athree-dimensional wiring 106 in which at least a part of the wiringconductor 105 is embedded in the recessed gutter for wiring 103.According to the three-dimensional structure 200 configured as describedabove, since at least a part of the wiring conductor 105 is embedded inthe recessed gutter for wiring 103 extending between mutuallyintersecting adjacent faces of the three-dimensional structure 200 (whenreferring to FIG. 12, an upper surface 200 a of the upper rowconfiguring a difference in level, a vertical side face 200 bconfiguring a difference in level, and an upper surface 200 c of thelower row configuring a difference in level), even if the line width ofthe wiring 106 is thin and narrow, the adhesive strength of the wiring106 to the three-dimensional structure 200 is improved. Consequently,even if the wiring 106 passes through the corner part of a mountain lineprotruding outward of the three-dimensional structure 200 (whenreferring to FIG. 12, the corner part where the upper surface 200 a ofthe upper row and the vertical side face 200 b intersect), problems suchas the falling and dislocation of the wiring 106 can be reduced.Moreover, since at least a part of the wiring conductor 105 is embeddedin the recessed gutter for wiring 103, problems such as the wiring 106being disconnected due to physical external force can also be reduced.

The wiring 106 is a three-dimensional wiring that is provided on thesurface of the three-dimensional structure 200, and the wiring is formedso as to creep along the surface of the three-dimensional structure 200while being in contact with such surface. Accordingly, there is no needto give consideration to the phenomena such as a wire sweep in the wirebonding, and extremely high wiring density can be achieved. Moreover, ifthe entire wiring conductor 105 is embedded in the recessed gutter forwiring 103, the wiring 106 will not be easily affected from the outside,and problems such as the falling, dislocation and disconnection of thewiring 106 can be inhibited more effectively.

The three-dimensional structure 200 may be a resin molded product or aninorganic insulating molded product. Moreover, the three-dimensionalstructure 200 may be an integration as a result of separately preparingthe components and thereafter integrating such components. For example,it may be a complex like a semiconductor device in which, as a result ofa semiconductor chip being mounted on an insulating base material, anddifference in level was created across the entirety thereof. Otherwise,the three-dimensional structure 200 may be an integration where therespective components are integrated from the very beginning. This kindof compact is preferably prepared by injection molding from theperspective of production efficiency. Specific materials and modes incases where the three-dimensional structure 200 is, for example, acircuit board or a resin molded product are explained below. Meanwhile,if the three-dimensional structure 200 is an inorganic insulating moldedproduct, for example, various ceramic compacts such as ceramicsubstrates produced by sintering a green sheet obtained by tape-moldinga slurry in which an organic binder or aqueous solvent is mixed anddispersed in the glass ceramic powder or the like can be favorablyadopted.

If the three-dimensional structure 200 is, for example, a circuit boardor a resin molded product, there is no particular limitation in thematerials that can be used in the production of the three-dimensionalstructure 200, and various organic base materials and inorganic basematerials that have been conventionally used for the production ofcircuit boards can be used. As specific examples of an organic basematerial, there are the based materials made of epoxy resin, acrylicresin, polycarbonate resin, polyimide resin, polyphenylene sulfideresin, polyphenylene ether resin, cyanate resin, benzoxazine resin,bismaleimide resin, and the like.

As the epoxy resin, there is no particular limitation so as long as itis epoxy resin configuring the various organic substrates that can beused in the production of a circuit board. Specifically, for example,bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenolS-type epoxy resin, aralkyl epoxy resin, phenol novolac-type epoxyresin, alkyl phenol novolac-type epoxy resin, biphenol-type epoxy resin,naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin,aromatic aldehyde containing phenols and phenolic hydroxyl group andepoxy compound of its condensation product, triglycidyl isocyanurate,alicyclic epoxy resin and the like may be used. In addition, brominatedor phosphorus-modified epoxy resin, nitrogen-containing resin,silicon-containing resin and the like for providing flame resistance mayalso be used. Moreover, as the epoxy resin and resin, the foregoingepoxy resins and resins may be used alone or in combination of two ormore types.

When configuring the three-dimensional structure 200 with the respectiveresins, generally speaking, a curing agent is added for hardening theresin. There is no particular limitation in the curing agent so as longas it can be used as a curing agent. Specifically, for example,dicyandiamide, phenolic curing agent, acid anhydride curing agent,aminotriazine novolac curing agent, cyanate resin and the like may beused.

As the phenolic curing agent, for example, a novolac type, an aralkyltype, a terpene type or the like may be used. In addition,phosphorus-modified phenol resin, phosphorus-modified cyanate resin, orthe like for providing flame resistance may also be used. Moreover, asthe curing agent, the foregoing curing agents may be used alone or incombination of two or more types.

Since a concave part 3 for the circuit is formed as the circuit patternon the surface of the three-dimensional structure 200 in the wiringgutter forming step based on laser beam machining, it is preferable touse resin or the like with favorable absorptance (UV absorptance) oflaser beams in a wavelength region of 100 nm to 600 nm. For example,specifically, polyimide resin or the like may be used.

The three-dimensional structure 200 may contain a filler. As the filler,inorganic fine particles or organic fine particles may be used, andthere is no particular limitation. As a result of containing a filler,the filler will be exposed on the laser beam machining part and theadhesion of the plating (conductor 5) and the resin (three-dimensionalstructure 200) based on the unevenness of the filler will improve.

As the materials for configuring the inorganic fine particles,specifically, for example, high-dielectric filling materials such asaluminum oxide (Al₂O₃), magnesium oxide (MgO), boron nitride (BN),aluminum nitride (AlN), and silica (SiO₂); magnetic filling materialssuch as hard ferrite; inorganic flame retardants such as magnesiumhydroxide (Mg(OH)₂), aluminum hydroxide (Al(OH)₂), antimony trioxide(Sb₂O₃), antimony pentoxide (Sb₂O₅), guanidine salt, zinc borate, andzinc stannate; talc (Mg₃(Si₄O₁₀)(OH)₂), barium sulfate (BaSO₄), calciumcarbonate (CaCO₃), mica and the like may be used. As the inorganic fineparticles, the inorganic fine particles may be used alone or incombination of two or more types. Since these inorganic fine particleshave a high degree of freedom of thermal conductivity, relativepermittivity, flame resistance, particle size distribution, and colortone, they can be highly tilled easily based on appropriate blending andparticle size design when selectively exhibiting the intended function.Moreover, although there is no particular limitation, it is preferableto use a filler having an average particle size that is not greater thanthe thickness of the insulating layer; specifically, a filler having anaverage particle size of preferably 0.01 μm to 10 μm, and morepreferably 0.05 μm to 5 μm.

Moreover, the inorganic fine particles may be subject to surfacetreatment with a silane coupling agent for increasing the dispersibilityin the three-dimensional structure 200. Moreover, the three-dimensionalstructure 200 may also contain a silane coupling agent for increasingthe dispersibility of the inorganic fine particles in thethree-dimensional structure 200. There is no particular limitation inthe silane coupling agent that may be used. Specifically, for example,silane coupling agents of epoxy silane, mercapto silane, amino silane,vinyl silane, styryl silane, methacryloxy silane, acryloxy silane,titanate and the like may be used. As the silane coupling agent, theforegoing silane coupling agents may be used alone or in combination oftwo or more types.

Moreover, the three-dimensional structure 200 may contain a dispersantfor increasing the dispersibility of the inorganic fine particles in thethree-dimensional structure 200. There is no particular limitation inthe dispersant that may be used. Specifically, for example, dispersantsof alkyl ether, sorbitan ester, alkyl polyether amine, macromoleculardispersant and the like may be used. As the dispersant, the foregoingdispersants may be used alone or in combination of two or more types.

Moreover, as specific examples of the organic fine particles that can beused as the filler, used may be, for example, rubber fine particles andthe like.

There is no particular limitation in the form of the three-dimensionalstructure 200. Specifically, it may be a sheet, a film, a prepreg, athree-dimensionally shaped compact or the like. There is no particularlimitation in the thickness of the three-dimensional structure 200, and,for example, in the case of a sheet, a film, a prepreg or the like, thethickness is, for example, 10 to 2000 μm, preferably 10 to 500 μm, morepreferably 10 to 200 μm, more preferably 20 to 200 μm, and morepreferably around 20 to 100 μm.

Moreover, the three-dimensional structure 200 may be formed into athree-dimensionally shaped compact by placing the material to become thethree-dimensional structure 200 in, for example, a mold or a frame, andperforming pressurization and hardening thereto, or a sheet, a film or aprepreg may be punched and hardened, or hardened through heating andpressurization in order to form the three-dimensionally shaped compactor the like.

As shown in FIG. 12, the pad part 107 may also be provided on thesurface of the three-dimensional structure 200. The pad part 107 is anelectrode pad that is in conduction with the internal circuit of thethree-dimensional structure 200, or a bonding pad for mountingcomponents on the three-dimensional structure 200, or the like. If thewiring 106 is connected to the electrode pad 107, the wiring 106 will beconnected to the internal circuit of the three-dimensional structure 200that is in conduction with the electrode pad 107. Meanwhile, if thewiring 106 is connected to the bonding pad 107, the wiring 106 will beconnected to the components mounted on the bonding pad 107.

In the foregoing case, as shown in FIG. 13, the pad part 107 may beformed integrally with the wiring 106 by being embedded on the surfaceof the three-dimensional structure 200 (by embedding a part or all ofthe pad part 107). As the method of forming the pad part 107 integrallywith the wiring 106 by being embedded on the surface of thethree-dimensional structure 200, for example, in the wiring gutterforming step of FIG. 9B described above, a hole for the pad part isformed in succession with the wiring gutter 103, in the catalystdepositing step of FIG. 9C described above, the plating catalyst 104 isalso deposited in the hole for the pad part, in the coating removingstep of FIG. 9D described above, the plating catalyst 104 in the holefor the pad part is caused to remain, and in the plating processing stepof FIG. 9E described above, the plated metal 105 is also precipitated inthe hole for the pad part via electroless plating so as to form the padpart 107. Note that, in FIG. 13, reference numeral 300 shows thesemiconductor device in which a component 110 such as a semiconductorchip is mounted on the pad part 107 of the three-dimensional structure200.

Meanwhile, as shown in FIG. 14, the pad part 107 may be mountedsubsequently on the surface of the three-dimensional structure 200separately from the wiring 106 after the wiring 106 is formed. However,in the foregoing case, as shown in FIG. 14A, if the entire wiringconductor 105 is embedded in the recessed gutter for wiring 103, sincethe wiring conductor 105 is not protruding outside the surface of thethree-dimensional structure 200, if the end part of the wiring 106 andthe end part of the pad part 107 are merely placed together, the wiringconductor 105 and the pad part 107 cannot achieve a favorable contact,and a connection failure will occur. Thus, as shown in FIG. 14B, if theentire wiring conductor 105 is embedded in the recessed gutter forwiring 103, it is important to place the pad part 107 on the end part ofthe wiring 106 by being overlapped in a predetermined amount so that thewiring conductor 105 and the pad part 107 will contact each otherreliably.

With the example illustrated in FIG. 12, the wiring 106 extends acrossthree mutually intersecting adjacent faces 200 a, 200 b, 200 c of thethree-dimensional structure 200, but without limitation thereto, it mayalso extend across two adjacent faces 200 a, 200 b:200 b, 200 c orextend across four or more adjacent faces. Moreover, the wiring 106 maypass through a corner part of the mountain line, pass through a cornerpart of a valley line, or pass through both corner parts. Moreover, thewiring 106 is not limited to a linear shape, and may extend in a curvedshape, or be branched as illustrated in FIG. 12. Moreover, for example,the wiring 106 may also extend in the horizontal direction across thevertical side faces configuring the difference in level in FIG. 12.

It is preferred that, in the three-dimensional structure 200, at least apart of the recessed gutter for wiring have a width of 20 μm or less.More preferably, the width of at least a part of the recessed gutter forwiring is 20 to 0.5 μm. Even more preferably, the width of at least apart of the recessed gutter for wiring is 15 μm or less. Note that thewidth of the wiring gutter here is the width indicated by the letter Lin FIG. 22.

In regard to the wiring that is configured by embedding at least a partof the wiring conductor in the recessed gutter for wiring, it ispreferred that at least a part of the distance between adjacent wiringsin a wiring pattern (distance between wirings) be 50 μm or less. Morepreferably, at least a part of the distance is 30 μm or less, and evenmore preferably 20 μm or less. A more preferred range of the distancebetween wirings is 20 to 0.5 μm. The distance between wirings here isthe distance indicated by the letter S in FIG. 22.

One aspect of the three-dimensional structure with wirings according tothe present embodiment, therefore, has an advantage in which theelectrical interconnection line density can be improved more than whenconfiguring an electrical connection using the conventional wire bondingmethod. For example, it is more difficult for the wire bonding method toimprove the wiring density than for the three-dimensional structure ofthe present application that is provided with wirings, for the followingreasons: with the wire bonding method, the wire spacing cannot benarrowed in consideration of the sweep amount of the wire; and, becausethe wire for electrically connecting the electrode pads by means of wirebonding is in the air between the electrode pads, some sort of externalforce applied to the wire, such as resin that is applied to the bondedwire in order to seal the surface mounted components, causes a wire flowand poor connection and causes the wire to move and come into contactwith an adjacent wire, leading to electric failure such as shortcircuits. The wire bonding also lacks flexibility in the design of theinterconnect line because wire pads need to be arranged in a regularmanner.

Third (2) Embodiment

Another embodiment of the three-dimensional structure 200 is athree-dimensional structure that has a concave-convex form including agutter for wiring having at least partially a width of 20 μm or less,wherein at least a part of a wiring conductor is embedded in the gutterfor wiring, and a wiring that extends in such a manner as to creep alongthe concave-convex form is provided.

FIGS. 23 and 24 are schematic diagrams explaining the three-dimensionalstructure 200 of the present embodiment. Note that, in FIGS. 23 and 24,reference numeral 901 represents an insulating base material, 901 a anelectrode pad, 902 a semiconductor chip, 902 a a pad part, 905 a gutterfor wiring, and 907 a wiring (wiring conductor).

As illustrated in FIG. 23, in the three-dimensional structure of thepresent embodiment the gutter for wiring 905 is provided on the surfaceof the insulating base material 901 and the surface of the semiconductorchip 902. Thus, the surface of this gutter for wiring 905 is providedwith a concave-convex form including a concave form.

As shown in FIG. 24 illustrating how the wiring 907 is formed byembedding a conductor in the gutter for wiring 905 of FIG. 23, thewiring 907 is a three-dimensional wiring that is provided on the surfaceof the three-dimensional structure, and the wiring 907 is formed so asto creep along the surface of the three-dimensional structure whilebeing in contact with this surface. Accordingly, there is no need togive consideration to the phenomena such as a wire sweep in the wirebonding, and extremely high wiring density can be achieved.

For instance, a high-density wiring pattern that has a wiring width of20 μm or less, L (wiring width)/S(distance between wirings): 20 μm/50 μmor less, or L/S: 20 μm/20 μm or less, can be formed as well.

Also, as shown in FIG. 24, the wiring conductor 907 may be partiallyembedded in the gutter for wiring 905 shown in FIG. 23, and the otherportions of the wiring conductor 907 may be outside the surface of thethree-dimensional structure. Needless to say, if the entire wiringconductor 907 is embedded in the gutter for wiring 905, the wiring willnot be easily affected from the outside, and problems such as thefalling, dislocation and disconnection of the wiring can be inhibitedmore effectively. In the foregoing case, the surface of the wiringconductor 907 may be flush with the surface of the three-dimensionalstructure, or may be retreated more inward of the gutter for wiring 905than the surface of the three-dimensional structure.

In the three-dimensional structure, if the pad part is provided on thesurface of the three-dimensional structure, and the wiring is connectedto the pad part, the wiring will be connected to the internal circuit ofthe three-dimensional structure that is in conduction with the pad part,or a component or the like mounted on the pad part.

In such a case, the three-dimensional structure of the presentembodiment is preferably a three-dimensional structure that has aconcave-convex form including a recessed wiring gutter for wiring and arecessed hole part for a pad, which is deeper than the recessed wiringgutter. In this type of three-dimensional structure, at least a part ofthe wiring conductor and at least a part of a conductor for a pad partare embedded in the recessed gutter for wiring and the recessed holepart for a pad, and wirings that extend in such a manner as to creepalong the concave-convex form of the three-dimensional structure areprovided.

Note that the concave-convex form described in the present embodimentincludes a gutter concave-convex form of the gutter for wiring 905 and astep concave-convex form mounted with, for example, the semiconductorchip 902 as shown in FIGS. 23 and 24. FIG. 24 shows a state in which thewiring 907 and the pad part 902 a are configured by embedding at least apart of the conductor in the gutter concave-convex form, wherein thewiring 907 extends in such a manner as to creep along the concave-convexform (including the step concave-convex form) of the three-dimensionalstructure.

Moreover, the thickness of the conductor that is embedded in therecessed gutter for wiring and the recessed hole part for a pad maypartially vary. Alternatively, the depth of the gutter for wiring andthe depth of the recessed hole part for a pad may also partially vary inthe mixture of wiring patters of different sizes, so that in a partthereof, for example, the adhesion of the wiring and the pad part can beimproved.

Furthermore, in the present embodiment, at least a part of the pad partmay be formed on the wiring that is configured by embedding at least apart of the conductor in the gutter for wiring formed on the surface ofthe three-dimensional structure.

A metal conductor that is made from metal foil or by plating,deposition, sputtering or the like is preferably used as the wiringconductor that can be used in the present embodiment. On the other hand,it is preferred not to use a wiring that is obtained by formingconductive ink or conductive paste, which is obtained by mixing metalfine particles in a dispersion medium, into a pattern by a printing orapplication method and then thermally treating the resultant pattern.The reason thereof is as follows. Specifically, a wiring formed fromconductive ink or conductive paste including conductive metal fineparticles is a wiring for a sintered body obtained by continuouslyfusing or bringing the fine particles into contact with each other. Theelectrical characteristics such as a specific resistance of such awiring are likely to be changed depending on the heat treatmentcondition/environment. For example, such a wiring has a higher specificresistance and less of the electrical characteristics compared to ametal conductor that is made from metal foil or by plating, deposition,sputtering or the like. In addition, a wiring formed by sintering theconductive metal fine particles has a large number of voids therein anda low bulk density, which might cause a reduction in the mechanicalstrength of the wire itself.

In the present embodiment, it is preferred that the bulk density of ametal coating of each of metal layers in the formed metal wiring be 1 to0.2 times or 1 to 0.5 times of the true density of the metal.

Also, the ratio of the area of voids observed in the cross section ofthe metal wiring to the cross-sectional area of the metal wiring part,i.e., the ratio of the voids observed in the metal wiring as a result ofobserving the cross section of the metal wiring part, is preferably 50%or less, more preferably 25% or less, and even more preferably 15% orless.

Therefore, a metal wiring made from metal foil or by plating,deposition, sputtering or the like is preferably used as the wiringconductor.

In addition, the metal contained in the metal wiring is at least onetype of metal selected from copper (Cu), nickel (Ni), cobalt (Co),aluminum (Al) and the like. Above all, copper is preferred due to itsexcellent conductivity. Especially a copper wiring that is made frommetal foil or by plating, deposition, sputtering or the like or a metalwiring containing copper described above is favorably used due to itslow specific resistance.

On the other hand, for example, the electrical resistivity of copperfine particles contained in conductive ink or conductive paste as themain component is low, but the wiring resistance of a sintered body thatis produced as a wiring from conductive metal fine particles becomeshigh. This is because copper is easily oxidized and oxidation of thecopper metal fine particles promotes fusion between the copper fineparticles upon thermal treatment, increasing the specific resistance ofthe resultant copper wiring of the sintered body. Consequently,significant wiring delay occurs.

In the present embodiment, the specific resistance of a copper film partof a copper wiring or a metal wiring containing copper is preferablyless than 10 μΩcm, more preferably less than 5 μΩcm, or even morepreferably less than 3 μΩcm.

Note that because the three-dimensional structure of the presentembodiment has the recessed gutter for wiring, at least a part of whichhas a width of 20 μm or less, at least a part of the resultant wiringalso has a width of 20 μm or less. It is more preferred that at least apart of the resultant wiring have a width of 20 to 0.5 μm. It is evenmore preferred that at least a part of the resultant wiring have a widthof 15 μm or less.

Moreover, according to the present embodiment, at least a part of thewiring conductor described above preferably has a film thickness of 0.1to 10 μm, or more preferably approximately 1 to 5 μm.

At least a part of the recessed gutter for wiring according to thepresent embodiment preferably has a depth of 1 to 25 μm, more preferably3 to 22 μm, or even more preferably approximately 3 to 15 μm.

The configurations of the present embodiment other than those describedabove are not particularly limited and can be implemented by the sameembodiment as the one described above, if necessary.

Fourth Embodiment

The same reference numeral is used for members which are the same as orcorrespond to the members of the third embodiment, and only thecharacteristic portions of the fourth embodiment are explained. As shownin FIG. 15, while using the configuration of the three-dimensionalstructure 200 of the third embodiment as the premise, this fourthembodiment relates to a three-dimensional structure 200 including amultilayered circuit board 120, wherein an end part (shown with a blackcircle in the diagram) of the internal circuits 120 a faces a verticalwall 200 b of the side face of the multilayered circuit board 120, and awiring 106 realizes an interlayer connection of the internal circuits120 a of the multilayered circuit board 120 by being connected to theend part of the internal circuits 120 a. In this case also, at least apart of the wiring conductor may not be embedded in the recessed gutterfor wiring across the entire length of the recessed gutter for wiring,or it may be embedded at one portion, embedded at a plurality ofportions, or embedded partially or intermittently in the entire lengthof the recessed gutter for wiring. Moreover, the recessed gutter forwiring extends across mutually intersecting adjacent faces or on aplanar surface or a curved surface (including a bent curved surface, aconcave curved surface, a convex curved surface, and a curved surface ofthe combinations thereof) of the three-dimensional structure.

According to the three-dimensional structure 200 configured as describedabove, the wiring 106 functions as an external wiring for achieving theinterlayer connection. In other words, forming a via hole as a hole forinterlayer connection is conventionally known as a technique ofinterlayer connection in the multilayered circuit board 120. However,since a via hole is disposed on the internal circuit of the multilayeredcircuit board 120, there was a problem in that the wiring effective areaof the internal circuit would decrease by the size of the via holesdisposed thereon. The three-dimensional structure 200 of the fourthembodiment can avoid this problem since the embedded-type wiring 106that passes through the vertical wall 200 b of the side face of themultilayered circuit board 120 achieves the interlayer connection of themultilayered circuit board 120. Moreover, the external wiring 106 forachieving the interlayer connection can be easily provided on thevertical wall 200 b of the multilayered circuit board 120.

As illustrated in FIG. 15, the wiring 106 that passes through thevertical wall 200 b of the side face of the multilayered circuit board120 may take a detour for connecting to the internal circuit 120 a ofthe respective layers, obliquely pass through the vertical wall 200 b,or pass through the vertical wall 200 b so that it is not connected toan internal circuit of a predetermined layer.

Fifth Embodiment

An embodiment of a case where the three-dimensional structure isconfigured such that the semiconductor chip mounted on the insulatingbase material is coated with insulating resin (as described above, aninsulating organic material such as resin or an insulating organicmaterial such as ceramics as represented by silica (SiO2) may also beused in substitute for the insulating resin) is now explained. Note thatthe same reference numeral is used for members which are the same as orcorrespond to the members of the preceding embodiment, and only thecharacteristic portions of the fifth embodiment are explained. FIG. 16is a cross section showing a three-dimensional structure 500 accordingto the fifth embodiment. The three-dimensional structure 500 is asemiconductor device in which a semiconductor chip 503 mounted on aninsulating base material 501 is coated with insulating resin 505. Athree-dimensional wiring 511 is provided on the surface of thesemiconductor device 500. Specifically, the three-dimensional wiring 511is provided to the surface of the semiconductor device 500 as a resultof a recessed gutter for wiring 507 extending between mutuallyintersecting adjacent faces of the semiconductor device 500 beingformed, and at least a part of a wiring conductor 510 being embedded inthe recessed gutter for wiring 507. The semiconductor chip 503 may becoated with the insulating resin 505 in its entirety, or may be coatedpartially only at the portion where the wiring 511 is to be formed. Inthis case also, at least a part of the wiring conductor may not beembedded in the recessed gutter for wiring across the entire length ofthe recessed gutter for wiring, or it may be embedded at one portion,embedded at a plurality of portions, or embedded partially orintermittently in the entire length of the recessed gutter for wiring.Moreover, the recessed gutter for wiring extends across mutuallyintersecting adjacent faces or on a planar surface or a curved surface(including a bent curved surface, a concave curved surface, a convexcurved surface, and a curved surface of the combinations thereof) of thethree-dimensional structure.

Another end of a connection line 512 in which one end leads to a bondingpad 504 of the semiconductor chip 503 faces the surface of theinsulating resin 505, and the wiring 511 connects the other end of theconnection line 512 and the electrode pad 502 of the insulating basematerial 501.

This kind of semiconductor device 500 can be produced, for example,based on the following production method.

Moreover, as shown in FIG. 17A, the semiconductor chip 503 mounted onthe insulating base material 501 is coated with the insulating resin 505(resin coating step). As the usable insulating resin 505, resin sealmaterials that have been generally used from the past for sealing thesurface of a semiconductor chip in order to protect the semiconductorchip can be used without any particular limitation. Moreover, withrespect to the technique of coating the semiconductor chip 503 with theinsulating resin 505, resin sealing techniques that have been generallyused from the past for sealing the surface of a semiconductor chip inorder to protect the semiconductor chip can be used without anyparticular limitation.

Subsequently, as shown in FIG. 17B, the resin coating 506 is formed onthe surface of the insulating resin 505 and the surface of theinsulating base material 501 (coating forming step). As the usable resincoating 506, for example, those similar to the resin coating 3 explainedin the first embodiment can be used without any particular limitation.

Subsequently, as shown in FIG. 17C, a wiring gutter 507 having a depththat is greater than the thickness of the resin coating 506 andincluding a communication hole 508 that leads to the bonding pad 504 ofthe semiconductor chip 503 is formed by performing laser beam machiningfrom an outer surface side of the insulating resin 505 or an outersurface side of the insulating base material 501 (wiring gutter formingstep).

Subsequently, as shown in FIG. 18A, the plating catalyst 509 or itsprecursor is deposited on the surface of the wiring gutter 507, forexample, as with the first embodiment (catalyst depositing step).

Subsequently, as shown in FIG. 18B, the resin coating 506 is removed bybeing dissolved or swelled as with the first embodiment (coatingremoving step).

Subsequently, as shown in FIG. 18C, after the resin coating 506 isremoved, the electroless plating coating 510 is formed, as with thefirst embodiment, only at a site where the plating catalyst 509 or aplating catalyst 509 formed from its precursor remains (platingprocessing step). The electroless plating coating 510 formed inside thecommunication hole 508 will configure the connection line 512. Insubstitute for forming the communication hole 508, the connection line512 made of a conductor extending outward from the bonding pad 504 ofthe semiconductor chip 503 may also be provided in advance.

As with the fifth embodiment, if the three-dimensional structure 500 isa three-dimensional structure configured such that the semiconductorchip 503 mounted on the insulating base material 501 is coated with theinsulating resin 505, since a recessed gutter for wiring 507 is notformed on the surface of the semiconductor chip 503 made of siliconwafer and a recessed gutter for wiring 507 is formed on the surface ofthe insulating resin 505, there is an advantage in that the recessedgutter for wiring 507 can be formed easily.

Moreover, the wiring 511 is a wiring for electrically connecting thebonding pad 504 of the semiconductor chip 503 to the electrode pad 502of the insulating base material 501 via the connection line 512.

The foregoing production method was related to the semiconductor chip503 mounted on the insulating base material 501, but it is not limitedthereto, and the production method can similarly applied to asemiconductor chip that is not mounted on an insulating base material, apassive element that is mounted on an insulating base material, or apassive element is not mounted on an insulating base material.

Moreover, although the foregoing production method was related to a caseof forming the wiring gutter 507 including the communication hole 508that leads to the bonding pad 504 of the semiconductor chip 503, it isnot limited thereto, and the production method can similarly applied toa wiring gutter which is in communication with another end of aconnection line in which one end leads to a bonding pad of thesemiconductor chip, a wiring gutter which is in communication withanother end of an interconnect line in which one end leads to thesemiconductor chip or the passive element, or a wiring gutter includinga connection hole leading to the semiconductor chip or the passiveelement.

Sixth Embodiment

Another embodiment of the three-dimensional structure configured suchthat a semiconductor chip mounted on an insulating base material iscoated with insulating resin (as described above, an insulating organicmaterial such as resin or an insulating organic material such asceramics as represented by silica (SiO₂) may also be used in substitutefor the insulating resin) is now explained. Note that the same referencenumeral is used for members which are the same as or correspond to themembers of the previous embodiments, and only the characteristicportions of the sixth embodiment are explained. FIG. 19A to FIG. 19C arecross sections showing mutually different examples of athree-dimensional structure 600 according to the sixth embodiment. Thethree-dimensional structure 600 is a semiconductor device in which aplurality of semiconductor chips 603 are mounted on an insulating basematerial 601 in a state of being stacked in multiple stages, and thesemiconductor chip 603 is coated with insulating resin 605. Thesemiconductor chip 603 may be coated with the insulating resin 605 inits entirety, or may be coated partially only at the portion where thewiring 611 is to be formed. Note that, in this case also, at least apart of the wiring conductor may not be embedded in the recessed gutterfor wiring across the entire length of the recessed gutter for wiring,or it may be embedded at one portion, embedded at a plurality ofportions, or embedded partially or intermittently in the entire lengthof the recessed gutter for wiring. Moreover, the recessed gutter forwiring extends across mutually intersecting adjacent faces or on aplanar surface or a curved surface (including a bent curved surface, aconcave curved surface, a convex curved surface, and a curved surface ofthe combinations thereof) of the three-dimensional structure.

Another end of an interconnect line 612 in which one end leads to thesemiconductor chip 603 faces the surface of the insulating resin 605,and the wiring 611 connects a plurality of semiconductor chips 603 byconnecting the other ends of the interconnect lines 612.

In the sixth embodiment, the three-dimensional structure 600 is astacked chip package for achieving the further downsizing and higherdensification among the multi chip modules.

Subsequently, an external wiring 611 for connecting the chips is formedon the vertical wall of the side face or the upper surface of thestacked chip package 600.

According to the stacked chip package 600 configured as described above,the wiring 611 will function as an external wiring for connecting thechips as an alternative to the conventional through silicon viatechnique or the multistage wire bonding technique. In other words, as atechnique for connecting semiconductor chips in a stacked chip package600 in which a plurality of semiconductor chips 603 are stacked inmultiple stages, conventionally known are the through silicon viatechnique and the multistage wire bonding technique. However, withthrough silicon via, since via is disposed on the circuit of asemiconductor chip 603, there was a problem in that the wiring effectivearea of the circuit in the chip 603 would decrease by the size of thedisposed via. Moreover, with multistage wire bonding, in addition to thelack of reliability as described in the background art, there areproblems in that the mounting area is large and that high densificationcannot be achieved. The stacked chip package 600 of the sixth embodimentforms an embedded-type external wiring 611 for connecting the chips onthe vertical wall of the side face or the upper surface of the stackedchip package 600, and the external wiring 611 connects the plurality ofchips built into the stacked chip package 600 via the interconnect line612. Thus, the foregoing problems can be avoided.

FIG. 19A shows a stacked chip package 600 where the thickness of theinsulating resin 605 of the upper most part of the stacked chip package600 is thin, and the external wiring 611 of the upper surface of thestacked chip package 600 is directly connected to the chip 603 of theuppermost layer.

Moreover, FIG. 19B shows a case of forming a vertical hole-typeconnection hole leading to the chip 603 of the upper most layer on theexternal wiring 611 of the upper surface of the stacked chip package 600since the thickness of the insulating resin 605 of the uppermost part ofthe stacked chip package 600 is thick, and the electroless platingcoating formed inside the connection hole (vertical hole) configuringthe interconnect line 612. In substitute for forming the connection hole(vertical hole), an interconnect line 612 made of a conductor thatextends from the semiconductor chip 603 toward the outside (vertically)may be provided in advance.

Moreover, FIG. 19C shows a case of forming a horizontal hole-typeconnection hole leading to the chip 603 of the upper most layer on theexternal wiring 611 of the vertical wall of the side face of the stackedchip package 600 since the thickness of the insulating resin 605 of theuppermost part of the stacked chip package 600 is thick, and theelectroless plating coating formed inside the connection hole(horizontal hole) configuring the interconnect line 612. In substitutefor forming the connection hole (horizontal hole), an interconnect line612 made of a conductor that extends from the semiconductor chip 603toward the outside (horizontally) may be provided in advance.

In FIG. 19A to FIG. 19C, reference numeral 607 shows a recessed gutterfor wiring and reference numeral 610 shows a wiring conductor.

Seventh Embodiment

Subsequently, a separate embodiment of the three-dimensional structureconfigured such that a semiconductor chip mounted on an insulating basematerial is coated with insulating resin (as described above, aninsulating organic material such as resin or an insulating organicmaterial such as ceramics as represented by silica (SiO₂) may also beused in substitute for the insulating resin) is now explained. The samereference numeral is used for members which are the same as orcorrespond to the members of the previous embodiments, and only thecharacteristic portions of the seventh embodiment are explained. FIG. 20is a cross section showing the three-dimensional structure 700 accordingto the seventh embodiment. The three-dimensional structure 700 is amemory card in which a memory package 720 is mounted on a support medium750. The memory package 720 is configured such that a semiconductor chip703 is mounted on an insulating base material 701, and the semiconductorchip 703 is coated with insulating resin 705. The semiconductor chip 703may be coated with the insulating resin 705 in its entirety, or may becoated partially only at the portion where the wiring 711 is to beformed. In this case also, at least a part of the wiring conductor maynot be embedded in the recessed gutter for wiring across the entirelength of the recessed gutter for wiring, or it may be embedded at oneportion, embedded at a plurality of portions, or embedded partially orintermittently in the entire length of the recessed gutter for wiring.Moreover, the recessed gutter for wiring extends across mutuallyintersecting adjacent faces or on a planar surface or a curved surface(including a bent curved surface, a concave curved surface, a convexcurved surface, and a curved surface of the combinations thereof) of thethree-dimensional structure.

In the memory card 700, formed on the surface of the memory package 720and the surface of the support medium 750 is a three-dimensional wiring711 in which at least a part of the wiring conductor 710 is embedded inthe recessed gutter for wiring 707. In other words, a recessed gutterfor wiring 707 extending between the mutually intersecting adjacentfaces of the memory card 700 is formed on the surface of the memory card700, and at least a part of the wiring conductor 710 is embedded in therecessed gutter for wiring 707. In FIG. 20, reference numeral 715 showsa pad part for electrically connecting to an external device.

With the memory card 700 configured as described above, a card case isno longer required, and the further downsizing of the memory card as aproduct can be achieved.

Eighth Embodiment

An embodiment of a case where three-dimensional structure is configuredsuch that the passive element is coated with an insulating resin (asdescribed above, an insulating organic material such as resin or aninsulating organic material such as ceramics as represented by silica(SiO₂) may also be used in substitute for the insulating resin) is nowexplained. Note that the same reference numeral is used for memberswhich are the same as or correspond to the members of the previousembodiments, and only the characteristic portions of the eighthembodiment are explained. FIG. 21 is a cross section showing athree-dimensional structure 800 according to the eighth embodiment. Thethree-dimensional structure 800 is a magnetic head module in which amagnetic head 820 is mounted on a harness 850. The magnetic head 820 isan electrical device configured such that a magnetic sensor 830 as apassive element is coated with insulating resin 805. The magnetic sensor830 may be coated with the insulating resin 805 in its entirety, or maybe coated partially only at the portion where the wiring 811 is to beformed. In this case also, at least a part of the wiring conductor maynot be embedded in the recessed gutter for wiring across the entirelength of the recessed gutter for wiring, or it may be embedded at oneportion, embedded at a plurality of portions, or embedded partially orintermittently in the entire length of the recessed gutter for wiring.Moreover, the recessed gutter for wiring extends across mutuallyintersecting adjacent faces or on a planar surface or a curved surface(including a bent curved surface, a concave curved surface, a convexcurved surface, and a curved surface of the combinations thereof) of thethree-dimensional structure.

In the magnetic head module 800, formed on the surface of the magnetichead 820 and the surface of the harness 850 is a three-dimensionalwiring 811 in which at least a part of the wiring conductor 810 isembedded in the recessed gutter for wiring 807. In other words, arecessed gutter for wiring 807 extending between the mutuallyintersecting adjacent faces of the magnetic head module 800 is formed onthe surface of the magnetic head module 800, and at least a part of thewiring conductor 810 is embedded in the recessed gutter for wiring 807.

In the magnetic head module 800, another end of an interconnect line 812in which one end leads to the magnetic sensor 830 faces the surface ofthe insulating resin 805, and the wiring 811 is connected to the otherend of the interconnect line 812. Accordingly, the wiring 811 becomes awiring that is electrically connected to the magnetic sensor 830 as apassive element via the interconnect line 812.

Since a recessed gutter for wiring 807 is not formed on the surface ofthe magnetic sensor 830 as a passive element and a recessed gutter forwiring 807 is formed on the surface of the insulating resin 805, thereis an advantage in that the recessed gutter for wiring 807 can be formedeasily.

In the magnetic head module 800, since the electrical device is amagnetic head 820, on the surface of the magnetic head 820, formed isthe three-dimensional wiring 811 in which at least a part of the wiringconductor 810 is embedded in the recessed gutter for wiring 807.

Moreover, when viewing the entire magnetic head module 800 in which themagnetic head 820 is mounted on the harness 850, on the surface of themagnetic head module 800, formed is the three-dimensional wiring 811 inwhich at least a part of the wiring conductor 810 is embedded in therecessed gutter for wiring 807.

In the eighth embodiment, although a case was explained where themagnetic sensor 830 as a passive element is coated with the insulatingresin 805 in a state of not being mounted on the insulating basematerial, the configuration is not limited thereto, and the magneticsensor 830 may also be coated with the insulating resin 805 in a stateof being mounted on the insulating base material.

Embodiments of the present invention were described in detail above, butthe foregoing explanations are merely an illustration in all aspects,and the present invention is not limited thereto. It should beunderstood that numerous modified examples that are not illustrated canbe envisioned without deviating from the scope of the present invention.

As described above, the present specification disclosed variousembodiments of the present invention. The main modes among the foregoingembodiments are summarized below.

One aspect of the present invention is a method of mounting asemiconductor chip for electrically connecting a bonding pad, which isprovided on a surface of a semiconductor chip disposed on an insulatingbase material surface, to an electrode pad corresponding to the bondingpad formed on the insulating base material surface, the method having: acoating forming step of forming a resin coating on a surface of a pathconnecting the bonding pad and the electrode pad; a wiring gutterforming step of forming, by laser beam machining, a wiring gutter havinga depth that is equal to or greater than a thickness of the resincoating along the path for connecting the bonding pad and the electrodepad; a catalyst depositing step of depositing a plating catalyst or aprecursor thereof a surface of the wiring gutter; a coating removingstep of removing the resin coating by causing this coating to dissolveor swell in a predetermined liquid; and a plating processing step offorming, after the resin coating is removed, an electroless platingcoating only at a site where the plating catalyst or a plating catalystformed from the plating catalyst precursor remains.

According to this method of mounting a semiconductor chip, the wiringfor connecting the semiconductor chip disposed on the insulating basematerial surface and the electrode of the insulating base materialsurface can be formed on the insulating base material surface and thesemiconductor chip surface in a manner of being formed along the wall ofthe semiconductor chip and the insulating base material surface. Sincethe wiring formed as described above is formed on the surface of theinsulating base material or the semiconductor chip, it will be strongerin comparison to the wiring formed with wire bonding. Moreover, thewiring will not be damaged due to resin pressure even during the resinsealing. Moreover, accurate wiring can be formed with a simple processby using laser beam machining.

Preferably, the foregoing method of mounting a semiconductor chipfurther comprises an electrolytic plating step of using the formedelectroless plating coating as an electrode and performing electrolyticplating in order to thicken a circuit. Although it is relativelytime-consuming since the thickening is achieved only with electrolessplating, according to the electrolytic plating step, since a wiring of athin film can be formed by performing electroless plating for a shortperiod of time and the formed electroless plating coating can thereafterbe used as the feed electrode, thickening can be achieved in a shortperiod of time.

In the foregoing method of mounting a semiconductor chip, preferably,the resin coating contains a fluorescent substance, and the methodfurther comprises an inspecting step of inspecting a coating removalfailure by using emission of light from the fluorescent substance afterthe coating removing step and before the plating processing step.According to this inspecting step, since the coating removal failure canbe confirmed, it is possible to inhibit the formation of the platingfilm at unwanted portions.

In the foregoing method of mounting a semiconductor chip, preferably,the resin coating is made of swellable resin that is peeled as a resultof being swelled in a predetermined liquid from the perspective offacilitating removal.

In the foregoing method of mounting a semiconductor chip, preferably,the thickness of the resin coating is 10 μM or less. If the thickness istoo thick, the dimension accuracy tends to deteriorate upon partiallyremoving the resin coating with laser beam machining, and, if thethickness is too thin, the formation of a coating with a uniform filmthickness tends to become difficult.

In the foregoing method of mounting a semiconductor chip, preferably,the resin coating is a coating that is formed by applying andsubsequently drying a suspension or an emulsion of an elastomer on theinsulating base material surface.

In the foregoing method of mounting a semiconductor chip, preferably,the resin coating is formed by transferring the swellable resin coatingformed on the support base material to the insulating base materialsurface.

Another aspect of the present invention is a semiconductor device,wherein a semiconductor chip including a bonding pad is disposed on aninsulating base material surface, and the bonding pad is connected to anelectrode pad formed on the insulating base material surface via aplating film formed on a surface of the semiconductor chip and on theinsulating base material surface.

Yet another aspect of the present invention is a method of connectingsemiconductor chips for mutually and electrically connecting bondingpats provided to a plurality of semiconductor chips disposed on aninsulating base material surface, the method having: a coating formingstep of forming a resin coating on a surface of a path connecting abonding pad formed on a first semiconductor chip and a bonding padformed on a second semiconductor chip; a wiring gutter forming step offorming, by laser beam machining, a wiring gutter having a depth that isequal to or greater than a thickness of the resin coating along thepath; a catalyst depositing step of depositing a plating catalyst or aprecursor thereof on a surface of the wiring gutter; a coating removingstep of removing the resin coating by causing this coating to dissolveor swell in a predetermined liquid; and a plating processing step offorming, after the resin coating is removed, an electroless platingcoating only at a site where the plating catalyst or a plating catalystformed from the plating catalyst precursor remains. According to thismethod of connecting semiconductor chips, since the wiring can be formedto go over the difference in level caused by the semiconductor chip, aplurality of semiconductor chips can be electrically connected on asubstrate with a simple method. Accordingly, the production of a multichip module and the like can be realized easily.

Yet another aspect of the present invention is a three-dimensionalstructure in which a wiring is formed on a surface, wherein, on thesurface of the three-dimensional structure, a recessed gutter for wiringis formed, extending between mutually intersecting adjacent faces or ona planar surface or a curved surface of the three-dimensional structure,and wherein at least a part of a wiring conductor is embedded in therecessed gutter for wiring. According to this three-dimensionalstructure, since at least a part of the wiring conductor is embedded inthe recessed gutter for wiring extending between mutually intersectingadjacent faces of the three-dimensional structure, even if the linewidth of the wiring is thin and narrow, the adhesive strength of thewiring relative to the three-dimensional structure is improved.Consequently, even if the wiring passes through the corner part of amountain line protruding outward of the three-dimensional structure,problems such as the falling and dislocation of the wiring can bereduced. Moreover, since at least a part of the plated metal is embeddedin the recessed gutter for wiring, problems such as the wiring beingdisconnected due to physical external force can also be reduced.

Yet another aspect of the present invention is a three-dimensionalstructure that has a concave-convex form including a gutter for wiringhaving at least partially a width of 20 μm or less, wherein at least apart of a wiring conductor is embedded in the gutter for wiring, and awiring that extends in such a manner as to creep along theconcave-convex form is provided.

The wiring is a three-dimensional wiring that is provided on the surfaceof a three-dimensional structure, and the wiring is formed so as tocreep along the surface of the three-dimensional structure while beingin contact with such surface. Accordingly, there is no need to giveconsideration to the phenomena such as a wire sweep in the wire bonding,and extremely high wiring density can be achieved.

For instance, at least a part of the wiring pattern can be formed toinclude a high-density wiring pattern that has a wiring width of 20 μmor less, L(wiring width)/S(distance between wirings): 20 μm/50 μm orless, or L/S: 20 μm/20 μm or less.

Moreover, only a part of the wiring conductor needs to be embedded inthe recessed gutter for wiring, and the other portions of the wiringconductor may be outside the surface of the three-dimensional structure.Needless to say, if the entire wiring conductor is embedded in therecessed gutter for wiring, the wiring will not be easily affected fromthe outside, and problems such as the falling, dislocation anddisconnection of the wiring can be inhibited more effectively. In theforegoing case, the surface of the wiring conductor may be flush withthe surface of the three-dimensional structure, or may be retreated moreinward of the recessed gutter for wiring than the surface of thethree-dimensional structure.

In the three-dimensional structure, if a pad part is provided on thesurface of the three-dimensional structure, and the wiring is connectedto the pad part, the wiring will be connected to the internal circuit ofthe three-dimensional structure that is in conduction with the pad part,or a component or the like mounted on the pad part.

In the three-dimensional structure, if the three-dimensional structureincludes a multilayered circuit board, an end part of an internalcircuit faces a vertical wall of a side face of the multilayered circuitboard, and the wiring forms an interlayer connection of internalcircuits of the multilayered circuit board by being connected to the endpart of the internal circuits, the wiring will function as an externalwiring for interlayer connection as a substitute for the technique offorming a via hole as the hole for conventional interlayer connection.Consequently, with the conventional technique of forming a via hole,there was a problem in that the wiring effective area of the internalcircuit would decrease by the size of the via holes disposed on theinternal circuit of the multilayered circuit board, but such a problemcan be resolved. Moreover, the external wiring for interlayer connectioncan be easily formed on the vertical wall of the multilayered circuitboard.

In the three-dimensional structure, if the three-dimensional structureis a semiconductor device in which a semiconductor chip is mounted on aninsulating base material, a three-dimensional wiring in which at least apart of the wiring conductor is embedded in the recessed gutter forwiring will be formed on the surface of the insulating base material orthe surface of the semiconductor chip. The wiring of the foregoing casebecomes, as described above, a wiring for electrically connecting thebonding pad provided to the surface of a semiconductor chip disposed onthe insulating base material surface to the electrode pad formed on theinsulating base material surface.

As other specific examples of the three-dimensional structure, thereare, for example, a stacked chip package in which a plurality ofsemiconductor chips are mounted in a state of being stacked in multiplestages on a three-dimensionally formed circuit board, multilayeredcircuit board, or insulating base material, a semiconductor deviceconfigured such that a semiconductor device (for instance, a memorypackage or the like) that is mounted on an insulating base material or asemiconductor chip that is not mounted on an insulating base material iscoated with insulating resin, a memory card in which the memory packageis mounted on a support medium, an electrical device (for instance, amagnetic head or the like) configured such that a passive element (forinstance, a resistor, a capacitor, a coil, various sensors or the like)that is mounted on an insulating base material or a passive element thatis not mounted on an insulating base material is coated with insulatingresin, and a magnetic head module or the like in which the magnetic headis mounted on a harness.

A semiconductor device in which a semiconductor chip is mounted, via thepad part, on the three-dimensional structure is a semiconductor devicein which a semiconductor chip is mounted on the three-dimensionalstructure wherewith a three-dimensional wiring, in which at least a partof the wiring conductor is embedded in the recessed gutter for wiring,is formed on its surface.

In the three-dimensional structure, if the three-dimensional structureis a semiconductor device in which a semiconductor chip is mounted on aninsulating base material and the semiconductor chip is coated withinsulating resin, a three-dimensional wiring in which at least a part ofthe wiring conductor is embedded in the recessed gutter for wiring willbe formed on the surface of the insulating base material or the surfaceof the insulating resin coating the semiconductor chip. Since a recessedgutter for wiring is not formed on the surface of the semiconductor chipmade of silicon wafer and a recessed gutter for wiring is formed on thesurface of the insulating resin, there is an advantage in that therecessed gutter for wiring can be formed easily.

In the three-dimensional structure, if the three-dimensional structureis a semiconductor device in which a plurality of semiconductor chipsare stacked in multiple stages on an insulating base material, and thesemiconductor chips are coated with insulating resin, athree-dimensional wiring, in which at least a part of the wiringconductor is embedded in the recessed gutter for wiring, will be formedon the surface of the stacked chip package in which further downsizingand higher densification can be sought among the multi chip modules.

In the three-dimensional structure, if one end of a connection line inwhich the other end leads to a bonding pad of the semiconductor chipfaces the surface of the insulating resin, and the wiring connects theone end of the connection line and the electrode pad of the insulatingbase material, the wiring becomes a wiring for electrically connectingthe bonding pad of the semiconductor chip to the electrode pad of theinsulating base material via the connection line.

In the three-dimensional structure, if one end of an interconnect linein which the other end leads to the semiconductor chip faces the surfaceof the insulating resin, and the wiring connects the plurality ofsemiconductor chips by connecting each interconnect line on the one end,the wiring will function as an external wiring for connecting thesemiconductor chips as an alternative to the conventional throughsilicon via technique or the multistage wire bonding technique. In otherwords, as a technique for connecting semiconductor chips in a stackedchip package in which a plurality of semiconductor chips are stacked inmultiple stages, conventionally known are the through silicon viatechnique and the multistage wire bonding technique. However, withthrough silicon via, since via is disposed on the circuit of asemiconductor chip, there was a problem in that the wiring effectivearea of the circuit in the chip would decrease by the size of thedisposed via. Moreover, with multistage wire bonding, in addition to thelack of reliability as described in the background art, there areproblems in that the mounting area is large and that high densificationcannot be achieved. In light of the foregoing problems, thethree-dimensional structure of the present configuration forms anembedded-type external wiring for connecting the chips on the verticalwall of the side face or the upper surface of the stacked chip package,and the external wiring connects the chips built into thethree-dimensional structure via the interconnect line. Thus, theforegoing problems can be avoided.

In the three-dimensional structure, if the semiconductor device is amemory package, a three-dimensional wiring, in which at least a part ofthe wiring conductor is embedded in the recessed gutter for wiring, willbe formed on the surface of the memory package.

Yet another aspect of the present invention is a memory card in whichthe memory package is mounted on a support medium, wherein, on a surfaceof the memory card, a recessed gutter for wiring is formed betweenmutually intersecting adjacent faces or on a planar surface or a curvedsurface of the memory card, and wherein at least a part of a wiringconductor is embedded in the recessed gutter for wiring. According tothe foregoing configuration, formed on the surface of the memory card isa three-dimensional wiring in which at least a part of the wiringconductor is embedded in the recessed gutter for wiring.

In the three-dimensional structure, if the three-dimensional structureis an electrical device in which a passive element is coated withinsulating resin, a three-dimensional wiring, in which at least a partof the wiring conductor is embedded in the recessed gutter for wiring,will be formed on the surface of the electrical device. Since a recessedgutter for wiring is not formed on the surface of the passive elementand a recessed gutter for wiring is formed on the surface of theinsulating resin, there is an advantage in that the recessed gutter forwiring can be formed easily.

In the three-dimensional structure, if one end of an interconnect linein which the other end leads to the passive element faces the surface ofthe insulating resin, and the wiring is connected to the one end of theinterconnect line, the wiring becomes a wiring that is electricallyconnected to the passive element via the interconnect line.

In the three-dimensional structure, if the electrical device is amagnetic head, a three-dimensional wiring, in which at least a part ofthe wiring conductor is embedded in the recessed gutter for wiring, willbe formed on the surface of the magnetic head.

Yet another aspect of the present invention is a magnetic head module inwhich the magnetic head is mounted on a harness, wherein, on a surfaceof the magnetic head module, a recessed gutter for wiring is formedbetween mutually intersecting adjacent faces or a planar surface or acurved surface of the magnetic head module, and wherein at least a partof a wiring conductor is embedded in the recessed gutter for wiring.According to the foregoing configuration, formed on the surface of themagnetic head module is a three-dimensional wiring in which at least apart of the wiring conductor is embedded in the recessed gutter forwiring.

Yet another aspect of the present invention is a method of producing athree-dimensional structure in which a wiring is formed on a surface,the method having: a resin coating step of coating, with insulatingresin, a semiconductor chip mounted or not mounted on an insulating basematerial or a passive element; a coating forming step of forming a resincoating on a surface of the insulating resin or on a surface of theinsulating base material; a wiring gutter forming step of forming, byperforming laser beam machining from an outer surface side of theinsulating resin or an outer surface side of the insulating basematerial, a wiring gutter which has a depth that is greater than athickness of the resin coating and which is in communication with oneend of a connection line in which the other end leads to a bonding padof the semiconductor chip, a wiring gutter which is in communicationwith one end of an interconnect line in which the other end leads to thesemiconductor chip or the passive element, a wiring gutter including acommunication hole leading to the bonding pad of the semiconductor chip,or a wiring gutter including a connection hole leading to thesemiconductor chip or the passive element; a catalyst depositing step ofdepositing a plating catalyst or a precursor thereof on a surface of thewiring gutter; a coating removing step of removing the resin coating bycausing the coating to dissolve or swell in a predetermined liquid; anda plating processing step of forming, after the resin coating isremoved, an electroless plating coating only at a site where the platingcatalyst or a plating catalyst formed from the plating catalystprecursor remains. According to this method of producing athree-dimensional structure, since a recessed gutter for wiring is notformed on the surface of a semiconductor chip made of silicon wafer orthe surface of the passive element and a recessed gutter for wiring isformed on the surface of the insulating resin, there is an advantage inthat the recessed gutter for wiring can be formed easily.

EXAMPLES

The production method according to the present embodiment is nowdescribed more concretely hereinafter using examples. It should be notedthat the scope of the present invention is not construed as beinglimited to the following examples in any way.

Example 1

First of all, the insulating resin layer was formed on a supportingsubstrate.

As a material for the insulating resin layer, a resin composition thatcontains bisphenol A-type epoxy resin (“850S” manufactured by DICCorporation), multifunctional epoxy resin (“VG310180M” manufactured byPrintec Corporation), dicyandiamide as a curing agent (“DICY”manufactured by Nippon Carbide Industries Co., Inc.),2-ethyl-4-methylimidazole as a curing accelerator (“2E4MZ” manufacturedby Shikoku Chemicals Corporation), spherical fused silica as aninorganic filler (“FB1SDX” with an average particle size of 1.7 μm,manufactured by Denki Kagaku Kogyo Kabushiki Kaisha), a silane couplingagent (“A-187” manufactured by Momentive Performance Materials Inc.),methyl ethyl ketone (MEK) as a solvent, and N, N-dimethylformamide(DMF), was used.

Three of this sheet-like insulating resin layer (with a thickness of 100μm) configured by this resin composition were stacked and placed on acircuit formation surface of the supporting substrate, and then a metalmold with an uneven pattern was placed on the outer surface of thisresultant stacked sheet configured by the resin composition. Thisstacked product was vacuum pressurized/heated at 2.0 Mpa and 130° C. forfive minutes and molded, which was then heated/cured at an increasedtemperature of 175° C. for 90 minutes, and thereafter the insulatingresin layers were cured. Subsequently, the metal mold with an unevenpattern was removed, so the resultant insulating resin layer on thesupporting substrate had a difference in level of 200 μm. Thisinsulating resin layer contains a filler of 75 wt % relative to thecured insulating resin layer.

As a result of observing the surfaces and cross section of theinsulating resin layer under an optical microscope, it was confirmedthat the filler was not exposed and that a surface resin layer wasformed.

A resin coating of styrene-butadiene copolymer (SBR) was formed on thesurface of the insulating resin layer into a thickness of 2 μm. Notethat the resin coating was formed by applying a methyl ethyl ketone(MEK) suspension (with an acid equivalent of 600, a particle size of 200nm, and a solid content of 15%, manufactured by Zeon Corporation) ofstyrene-butadiene copolymer (SBR) to a main surface of the epoxy resinbase material and then drying the resultant product at 80° C. for 30minutes.

Subsequently, the insulating resin layer with the resin coating thereonwas laser-machined to form gutters each having a substantially 20μm-wide and 10 μm-deep U-shaped cross section. Furthermore, gutters areformed in the same manner to obtain an insulation distance of 50 μm,completing the recessed gutters for wiring. As the gutters for wiring,recessed gutters for wiring were formed on an inclined plane of thelevel difference part, an upper planar surface of the level differencepart, and a bottom planar surface of the level difference part.

Next, the insulating resin layer in which the recessed gutters forwiring are formed was dipped in a cleaner conditioner (surfactantsolution, pH<1: C/N3320 manufactured by Rohm and Haas ElectronicMaterials LLC) and then washed with water. Subsequently, soft etchingwas performed with a sodium persulfate-sulfuric acid soft etching agentwith pH less than 1. Then, a pre-dipping step was performed using PD404(with pH less than 1, manufactured by Shipley Far East Ltd.).Subsequently, the insulating resin layer was dipped in an acidic Pd—Sncolloid solution (CAT44, manufactured by Shipley Far East Ltd.) of pH 1containing tin chloride and palladium chloride so as to adsorb palladiumin a tin-palladium colloid state into the insulating resin layer, thepalladium being a core for electroless copper plating. As a result, aplating catalyst or a precursor thereof was deposited on the surface ofthe insulating resin layer and the surface of the resin coating.

Subsequently, the insulating resin layer was dipped an acceleratorchemical solution of pH less than 1 (ACC 19E, manufactured by ShipleyFar East Ltd.) so as to generate a palladium core. This palladium coreis a plating core for electroless plating.

The insulating resin layer was then dipped in a sodium hydroxide aqueoussolution having a concentration of 5% and pH 14 for 10 minutes whilebeing treated with ultrasonic waves. As a result, the resin coating onthe surface (SBR coating) became swollen and was peeled nicely. At thatmoment, there were no fragments or cracks of the resin coating remainingon the surface of the insulating resin layer. The insulating resin layerwas then dipped in electroless plating solutions (CM328A, CM328L,CM328C, manufactured by Shipley Far East Ltd.) to carry out anelectroless copper plating process.

As a result of the electroless copper plating process, an electrolesscopper plating film having a thickness of 3 to 5 μm was precipitated.After observing, under an SEM (scanning microscope), the surface of theinsulating resin layer that was treated with electroless copper plating,an electroless plating film was precisely formed only at a machinedsection. This electroless plating film is a wiring layer. As a result ofobserving, under the SEM, the wiring layer on the electroless platingfilm by the U-shaped cross section in the width direction of therecessed gutters for wiring, the wiring layer being the electrolessplating film embedded in the recessed gutters for wiring on the inclinedplane of the level difference part, the upper planar surface of thelevel difference part, and the bottom planar surface of the leveldifference part in the completed wiring part, there were no voids formedin the wiring layer.

Example 2

With the insulation distance between the gutters of Example 1 changed to20 μm, recessed gutters for wiring were formed and the same processingwas carried out subsequently. As a result, the electroless copperplating film having a thickness of 3 to 5 μm was precipitated. As aresult of observing the electroless copper-plated surface of theinsulating resin layer under an SEM (scanning microscope), it wasconfirmed that an electroless plating film was precisely formed only ata machined section. In addition, as a result of observing the wiringlayer completed in Example 1 under the SEM, there were no voids formedin the wiring layer.

INDUSTRIAL APPLICABILITY

According to the present invention, a wiring for connecting thesemiconductor chip disposed on the insulating base material surface andthe electrode of the insulating base material surface or a plurality ofsemiconductor chips disposed on the insulating base material surface canbe formed on the insulating base material surface and the semiconductorchip surface in a manner of creeping along the wall of the semiconductorchip and the insulating base material surface. The wiring formed asdescribed above will be stronger in comparison to the wiring formed withwire bonding. Accordingly, the wiring will not be damaged due to resinpressure even during the resin sealing. Moreover, according to thepresent invention, since the adhesive strength of the wiring relative tothe three-dimensional structure is improved in the three-dimensionalstructure such as a semiconductor device in which a wiring is providedon its surface, problems such as the falling, dislocation and cut of thewiring can be reduced. Accordingly, the present invention can be broadlyapplied industrially in the technical field of mounting methods ofsemiconductor chips and three-dimensional structures in which a wiringis provided on its surface.

1. A three-dimensional structure that has a concave-convex formincluding a gutter for wiring having at least partially a width of 20 μmor less, wherein at least a part of a wiring conductor is embedded inthe gutter for wiring, and a wiring that extends in such a manner as tocreep along the concave-convex form is provided.